ASUS ZenFone 2 review: 5.5-inches of power-packed performance

“The world’s first smartphone with 4GB RAM. But is that all there’s to the ZenFone 2? Our review has the answer”

While the likes of Motorola and Xiaomi were in the spotlight last year because of their market-defining actions such as helping define the budget-performance category and starting exclusive online sales, ASUS’ ZenFone range of devices proved to be a sleeper hit of the year 2014. The devices were made available in a variety of screen sizes and price ranges to cover the entire spectrum. However, the middle member of the series, the ZenFone 5 (review) was instrumental in making ASUS a name to reckon with in the smartphone industry.

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However, with its spiritual successor, the second-gen ZenFone, ASUS isn’t just hoping for a hit, it’s looking for a blockbuster. The ASUS ZenFone 2 does have all the makings to be one and the company is also making the right kind of noises to promote it. Of course, the 4GB RAM might be a show stealer (available in the top-end variant, ZE551ML), but the device is fully loaded in other aspects as well. Whether or not these ingredients make the device worth a buy is what matters however, and that’s what we intend to find out in this review.

Specs at a glance

  • Measures 152.5 x 77.2 x 10.9mm
  • Weighs 170g
  • 5.5-inch display, featuring a resolution of 1,920 x 1,080 pixels
  • 2.3GHz quad-core processor
  • 4GB RAM
  • 32GB internal storage, expandable up to 64GB
  • 13MP primary camera with dual-tone LED flash
  • 5MP front-facing camera
  • Dual-SIM dual active support, Wi-Fi, Bluetooth, GPS and NFC
  • 3,000mAh battery
  • Android 5.0 with ZenUI
In a hurry? You can go through our at-a-glance review of the ASUS ZenFone 2

Inspired by LG, manufactured by ASUS

With smartphones becoming bigger, it’s become increasingly difficult to reach the frequently-used power / wake-up keys or the volume buttons with a single hand. Korean manufacturer LG came up with an interesting idea to tackle this issue – instead of the sides, these controls were offered at the rear of its 2013 flagship, the G2. LG’s reasoning was that the area at the back is where our fingers stay while holding the phone, and thus it’s easier to perform these actions. The brand then carried this ideology to its current flagship as well as its budget offerings. ASUS also seems to be in agreement with the Korean company as the ZenFone 2 features volume buttons at the back.

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The idea definitely makes sense – at least, theoretically, but in reality however, it’s more difficult to press these buttons to control the volume. What’s even more bewildering is the fact that ASUS hasn’t placed the power key at the back or on the side, and it’s available bang in the middle on the top. With the large footprint of the ASUS ZenFone 2, reaching the button to unlock the device or putting it to sleep becomes an exercise in itself. Thankfully though, we rarely needed to press it as the brand has offered a software feature for the same, which we’ll talk in the coming sections. For plugging in earphones, a 3.5mm socket is available alongside, while the micro-USB port is present at the bottom.

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The company has bigger ambitions with the ZenFone 5’s successor, and that’s apparent with its choice of phablet-class 5.5-inch display adorning the front. The front is minimal apart from the display panel, with the area above hosting the earpiece, front-facing camera and a few sensors. For navigation, the hardware buttons are available below followed by a metal bar having concentric circles, which lends an interesting look to the smartphone.

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The button placement isn’t the only thing that the Taiwanese brand has aped from LG, as its plastic body with brushed metal finish also seems to be inspired from the G3 (review | FAQs). While the device is constructed from plastic, the metallic finish helps it to look premium. At the rear, you’ll also find the primary shooter along with an LED flash module and a speaker grille further below. Prying open the back panel exposes the dual-SIM slots along with an expansion slot.

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Along with LG, ASUS has also taken inspiration from HTC as the ZenFone 2 is very ergonomic with a dual curve at the back. This makes it very comfortable to hold for long durations and compensates for its heft of 170g. The curve also gives the illusion that the phablet is slim, even though it measures 10.2mm around its waist. However, the phablet isn’t meant for one-hand usage and might seem unwieldy for people with small hands. While we find the device has solid build quality and is attractive looking, specifically when considering its price tag, the placement of the power button is a quibble we can’t let go of.

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The screening

Apart from increasing the size of the display, ASUS has also increased its resolution on the ZenFone 2 compared to its predecessor, the ZenFone 5. The full HD resolution offers a rich pixel density of 401ppi on the 5.5-inch display of the smartphone. This makes the text look sharper, while the IPS display panel manages to deliver excellent viewing angles. Brightness levels are also fine, if not the best, which means you might have to max the brightness for reading the display outdoors.

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Colour reproduction is good too, but in case it’s not as per your preferences, then you can choose one among many display modes provided in the settings with the Splendid app. You can choose the vivid mode or customise the contrast and hue yourself as well. Reading mode is another useful feature which tones down the brightness so that it can be used for long reading sessions. Combine that with the large screen size at your disposal, the ZenFone 2 becomes a capable eBook reader.

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To protect the display on the ASUS ZenFone 2 against scratches and minor knocks, the phablet gets a layer of Corning Gorilla Glass 3. There’s also a glove mode which increases the sensitivity of the touchscreen so that it can be used while wearing gloves, which is very useful.

The charm of Lollipop-based candy, crushed by ASUS’s Zen interface

While consumers lamented the fact that ASUS offered the ZenFone series with Android 4.3 Jelly Bean at the time of the crunchy 4.4 KitKat (even though the brand promised an update, which is yet to arrive), the Taiwanese company isn’t repeating the same mistake. It has offered the ZenFone 2 with the latest build of Android, i.e., 5.0 Lollipop.

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Sadly, you won’t notice this at first glance. ASUS has heavily modified the ZenFone 2’s interface with its custom skin monikered ZenUI. Starting from the lock screen to the home screens, from themes to icons – the brand has tweaked everything. It’s only when you swipe down to the bottom, you start finding some Lollipop goodness with the notification shade giving way to the rounded icons of the settings menu.

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We’ve already given a deep-dive look at the ZenUI while reviewing the ASUS ZenFone 5, and its successor also offers similar features such as Kids Mode and Easy Mode, along with adding some interesting functionality.

The device offers you complete control of the UI, allowing you to change the theme, scroll effects and even the icons. The app drawer lists all the apps, but you get numerous options to sort them. Along with sorting them alphabetically or by recency (in terms of their installation dates), you can also categorise apps in smart folders. We found it to be a very efficient and time-saving process to bucket various apps neatly in different folders.

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Along with ASUS’ suite of apps such as Do It Later, Party Link, Super Note, etc., the phablet also comes with a lot of preloaded apps. You’ll get most of Google apps as well as CleanMaster, TripAdvisor, etc. The device also offers 5GB cloud storage through its WebStorage service.

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The ASUS ZenFone 2 features support for gestures, which can work when its on standby as well. So, instead of trying to reach the power key, you can simply double tap the handset to wake it up or double tap again to put it to sleep. Similarly, you can draw various gestures such as ‘W’ to access the browser or ‘C’ to open the camera app directly.

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To make it easier to use the phablet-sized ZenFone 2, you can enable the one-hand mode by double clicking the home button. It reduces the viewing area, which can be moved on any side of the screen and you can also increase or decrease its size.

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The master of pixels and image-enhancing modes

The upgrades are carried over in the photography department as well. Instead of an 8-megapixel shooter in the ZenFone 5, the ASUS ZenFone 2 features a 13MP camera with a Toshiba lens and f/2.0 aperture. Assisting the snapper in the low-light conditions is a dual-tone LED flash that provides illumination in form of warmer and colder colours. The front shooter has also been bumped to 5MP for offering lovely selfies that will dazzle your Facebook friends or Instagram followers.

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The camera app on the phablet is loaded to the brim with a ton of features and modes on offer. Along with the usual options of turning on the flash, HDR mode, et. al, you can use different modes such as Manual. Compared to the automatic mode, manual offers you DSLR-like options to adjust ISO, exposure, shutter speed, etc. Some other useful modes are Depth of field, Super resolution, Beautify, and Effects among others. ASUS has also updated its proprietary PixelMaster technology to version 2.0, which promises to improve the photo quality with various algorithms. We also liked the ambient feature of the app which automatically prompts you to change the mode for best results.

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But all these specs and software features won’t matter if the quality isn’t good and we’re glad to say that the ZenFone 2’s shooter doesn’t disappoint. The cameras are able to capture good amount of details and colour fidelity. Be it landscape shots or close-up images, the quality is nice. ASUS’ also delivers on its promise of superb low-light performance with its unique pixel merging technology, with which it claims that the camera sensor can get 400 percent more light. However, it downsizes the resolution and captures the images in 3-megapixels, which means you can’t look for details in such shots. Another issue worth highlighting is that the use of specialised modes such as HDR and low-light result in artificial images with overexposed areas.

Here’s a gander at few of the shots clicked with the ASUS ZenFone 2. In case you want more in-depth look, then check out our camera review of ASUS’ latest offering.

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In terms of video recording, the device misses out on the high-def 4K video capture, which has become quite a rage now thanks to the proliferation of 4K TVs. However, it does get the usual 1080p video recording at 30fps. All in all, the camera quality delivered by the ZenFone 2 is good, but falls short against the OnePlus One (camera review) and Xiaomi Mi 4 (camera review).

Feel the power

While all the aspects of the latest ZenFone have received an upgrade, its internals are perhaps the most noteworthy example of this fact. Just a mention of 4GB RAM on a pocketable gadget can send anyone in a tizzy and that’s what happened when ASUS announced the ZenFone 2 at CES this year. The ASUS ZenFone 2 is the world’s first phone with 4 gigs of RAM and that’s complemented well with powerful hardware. As before, ASUS has chosen to get an Intel Inside logo on its offering, as its latest device also utilises Intel’s Atom Z3580 processor. The chipset, based on chipmaker’s latest Moorefield platform, promises better power efficiency thanks to its 22nm fabrication process. The processor comes with 64-bit architecture and offers four cores thrumming at 2.3GHz. Rounding up the core hardware is the PowerVR G6430 graphics chipset clocked at 533MHz.

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We’ve already taken a look at what this firepower can do when we ran synthetic benchmarks on the smartphone. Our real-life experience of using the ASUS’ phablet isn’t much different. There wasn’t even a single instance of lag or stutter while using the ZenFone 2, and that includes the times when multiple apps were running in the background or while playing heavy games. In fact, even with as many as 15 apps running behind the scenes, the phablet always had more than a gigabyte of RAM spare. Playing graphically-demanding titles was also a buttery smooth experience. We loved playing level after level on Asphalt 8 and Leo’s Fortune even for extended periods. Sadly, with all this power, the device quickly starts heating up, with temperature levels reaching as much as 40 degree Celsius.

For memory, the ASUS ZenFone 2 ships with 32GB of eMMC storage (the device is also available in a 64GB version), out of which users can access a little over 25.5GB space. While for most, it should be enough to install apps and storing the multimedia files, the handset also has a provision for extending the storage by an additional 64GB with the use of a microSD card. The mobile also boast USB On-the-Go capabilities, which means you can use your flash drives with it.

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The ZenFone 2 is one of the very few offerings that come with dual-SIM dual active support. Not just that, its primary SIM slot is also compatible with next-gen 4G networks, while its secondary slot can tether with 2G networks. You also get the usual connectivity features that include Wi-Fi, Bluetooth 4.0, NFC and GPS.

Power user by day, thirsty for power by night

In the smartphone colloquial, the popular dialogue from Spider Man would be on the lines of “With great power, comes the need of charging regularly”. While the ASUS ZenFone sips juice from a beefy 3,000mAh sealed unit, it’s unable to keep up with its raw power. With moderate usage of calls and internet usage via Wi-Fi, it might last about a day. However, use it for gaming, internet browsing with cellular data and GPS navigation and the battery drops like a ripe apple from the tree. It’s hardly able to last an entire working day with such usage.

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In our battery drain test, where we ran a 720p video on loop with Wi-Fi turned off and both the brightness and volume set at 50 percent level, the ASUS ZenFone 2 was able to continue for around eight hours and 30 minutes. While this isn’t exactly low, it’s average at best and we expected more from a device of its class.

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However, ASUS’ fast charge functionality comes in handy for charging the smartphone. Its charging adapter delivers an output voltage of 9V at 2A along with the standard 5V and 2A to charge it quickly. You can also extend the battery life with the use of various modes such as ultra-saving mode or specify your own settings for saving battery.

Setting a new benchmark in the mid-range segment

Right from the ZenFone 2’s display to its design, cameras and most importantly, its guts, ASUS hasn’t just brought a upgraded successor to the ZenFone 5, but has also upped its game against the competition. It’s spec sheet proves that and so does our experience.

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Have some questions about the ZenFone 2. We might have answered them in our FAQs

At this point, it’s important to give you an idea about the different variants of the ASUS ZenFone 2. While the one we’ve reviewed is the top-of-the-line offering from the brand, it also gets a sibling retailing at Rs 22,999, which has double the internal storage at 64GB. The other versions of the ZenFone 2 are available in the affordab;e territory, with the middle variant offering 2GB RAM, 16GB storage and different processor (Intel Z3560) with four cores clocked at 1.8GHz and priced at Rs 14,999. The base model (ZE550ML) of the series carries a sticker price of Rs 12,999 and comes equipped with similar hardware as the middle version, but its display resolution is lowered to 720p. For more details, you can read our comparison between the four models of the ASUS ZenFone 2.

ASUS ZenFone 2 different variants compared

While we can’t comment about the performance of the affordable devices in the ZenFone 2 portfolio, the upper end models of the range should definitely be among the top of your shortlist for purchasing a smartphone in the mid-budget segment. However, it’s still not a clear-cut choice in the price band, and faces a tough fight from the OnePlus One (review | cheatsheet) and the Xiaomi Mi 4 (review | cheatsheet). Both these rivals are very capable and offer powerful specs, with similar price tags. They also have better cameras and battery life, though the ZenFone 2 gets a slight edge because of its microSD card slot and dual-SIM dual active support.

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It’s clear that the interest levels in the ZenFone 2 are high because of its chart-topping 4 gigs of RAM, but that’s not enough to make it a no-brainer. It’s the combination of all aspects, such as the display, build quality and camera performance, and the phablet scores well in all these areas. Overall, the ASUS ZenFone 2 deserves our recommendation as the device to go for in the mid range, but not without careful consideration of what it brings to the table in comparison with its closest rivals.

Price: Rs 19,999

Editor’s rating: 8 / 10


  • Ergonomic design
  • Loaded internals
  • Expandable storage
  • Dual-SIM support with compatibility for 4G networks (on the primary SIM slot)


  • Average battery
  • ZenUI subdues Material Design language

Photos by Raj Rout. Video by Pratik Vyas