What's Hot: Great specs and features for the price. Works with any GSM carrier, no contract required. Fast performance.
What's Not: Cellular reception not quite as strong as competing phones. On the heavy side.
Reviewed May 21, 2015 by Lisa Gade, Editor
in Chief (twitter: @lisagade)
Just a week ago, we reviewed a relatively affordable unlocked Android smartphone with a big screen, solid specs and 4G LTE for the US market; and now we're doing it again with the Asus ZenFone 2. Android phones with good specs and LTE for $300 or less full retail with no contract are rare in the US, and that makes these good times for those of you who don't want a contract, aren't up for renewal on a contract or simply need to replace a lost or broken phone. The ZenFone 2 is available in two versions for $199 and $299. Both have 5.5", 1920 x 1080 full HD IPS displays, a good 13MP rear camera, front 5MP camera, dual band WiFi 802.11ac, Bluetooth, NFC and a microSD card slot. They're powered by Intel CPUs and the $199 model is clocked at 1.8 GHZ, has 2 gigs of RAM and 16 gigs of storage. The $299 has a 2.3 GHz Intel CPU, 4 gigs of RAM and 64 gigs of storage. That's pretty nice for the price. The US ZenFone 2 is available from Amazon.com (as are import models, make sure you choose the right phone).
What Does Unlocked Mean?
The Asus is an unlocked GSM world phone, and that means you can use it with any GSM carrier. In fact, it has a dual SIM design, a feature that's more popular overseas than in the US. That means you could use two AT&T SIM cards, or a T-Mobile and AT&T SIM card at the same time--any two GSM SIM cards you wish. The first card slot handles both voice and data, while the second handles voice and texts but not data. Why does this feature exist? Say you have a work and personal phone, but you don't want to take both with you on a trip: simply put both SIM cards in the Asus and you'll only need one phone.
Since it's a GSM phone it works with AT&T, T-Mobile, Cricket, Metro PCS, Walmart's Family Mobile and other GSM carriers. It does not work on Sprint, Virgin Mobile or Verizon since they use a different network technology called CDMA.
Design and Ergonomics
While the Alcatel OneTouch Idol 3 we just reviewed aims squarely at thinness and good looks, the Asus ZenFone 2 goes for high performance. It's not a particularly light phone and it's not thin, though the edges taper enough to make it look thin from the side. Like the LG G3 and LG G4, it curves to its widest point in the center, and it's fairly thick there. The curved shape is comfortable in hand and the back finish isn't high gloss so it's not slippery. The phone is encased in plastic, and Asus offers 4 colors-- silver, black, red and gold, all with a brushed faux aluminum finish that won't fool anyone. The ZenFone 2 isn't a bad looking phone in the least, but it's not sexy stylish like the leather-backed LG G4 or the glass and aluminum Samsung Galaxy S6. But for the price, it's certainly good looking enough.
Though the battery is sealed inside, the back is removable and you'll find a microSD card slot and two micro SIM card slots since this is a dual SIM phone. The back is a bit harder to remove compared to most phones, and we had to pull at the pry point and work a fingernail around the edge to get it off. Asus offers a nifty View Flip Cover Deluxe that replaces the back cover and has a front flap with a circular clear window where you can see a variety of info and notifications. NFC is embedded in the back cover, so keep that in mind if you intend to use the phone with mobile payment systems (the NFC chip will change if you switch backs or between the stock phone and phone plus Flip Cover).
Like LG, Asus places the volume buttons on the back of the phone where your index finger naturally falls (assuming a medium to large hand). Unlike LG, the power button is up top rather than nestled between the volume buttons. The good news is that you won't accidentally hit the power button when working the volume controls; the bad news is that the power button is on the top edge. Since the ZenFone 2 supports double tapping to wake and sleep the phone, you won't have to use the power button often. When the phone is sleeping you can use gestures like drawing the letter "c" to wake the phone and launch the camera. The volume controls have a hatched surface but not much shape to help with tactile feel, unlike the LG G4.
Like most phones, the ZenFone 2 has an ambient light sensor, proximity sensor and gyro. Asus went with hardware home, back and multitasking buttons, and these are capacitive rather than mechanical (they don't move or click). Oddly and inconveniently, these buttons aren't backlit, so they're hard to see in dim lighting. I do wonder why Asus didn't go with on-screen buttons instead.
Display
The ZenFone 2 has a pleasing 5.5" IPS display. Overseas, the lower end model has a 720p display, but both our $199 and $299 US models have full HD 1920 x 1080 screens. Asus offers a few color balance settings including the default standard mode, vivid and a reading mode that tunes down the colors a bit. The screen is colorful, though obviously not as hyper-vivid as Super AMOLED displays used on Samsung Galaxy high end models or as immediate looking as the iPhone 6 Plus display. Blacks are fairly black (rather than dark gray) and whites don't suffer a colorcast. Contrast is good and that results in sharp looking text and photos, as does the perfectly good 400 PPI pixel density. No, it's no QHD 2560 x 1440 resolution, but you won't find a phone with that resolution for $200 or $300 full retail. Honestly, you need a very good set of eyeballs to tell the difference between full HD and QHD on a smartphone. Brightness is good, though the display isn't as bright as the Samsung Galaxy S6 and iPhone 6/ iPhone 6 Plus, and that means it's a bit harder to see outdoors in bright sunlight.
Calling and Data
We have both the US model provided by Asus and the import model from Taiwan supplied by GearBest.com (an online importer of Asian phones). The US model supports AT&T and T-Mobile LTE 4G, along with some smaller GSM carriers' bands. The US model supports quite a few LTE bands: 1, 2, 3, 4, 5, 7, 8 and 20. You might even pick up LTE in the EU when travelling, but alas T-Mobile's newly launched band 12 isn't here (as a consolation, it's not yet a must-have band on T-Mobile). We noted that our US model's reception fell behind other recent phones on T-Mobile, with a 7 db weaker signal (a much improved 2 db weaker after a firmware update). AT&T fared better, though we saw some signal fluctuation that's unusual in our strong coverage area. Phone CPUs and cellular radios are paired together in a system-on-chip design (SoC), and that means this is Intel's first big foray into the US LTE market (Qualcomm had a near stranglehold here in the US for several years). We've already seen one firmware update that improved reception since Intel's still working out the kinks.
Call quality on both AT&T and T-Mobile was quite good with clear and full voice on both ends. Volume was average for a modern smartphone and the rear-firing speakerphone was adequate though not as useful as a front facing speaker. Data speeds were good on LTE.
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Asus ZenFone 2 vs. Alcatel OneTouch Idol 3 Comparison
Performance and Horsepower
Both ZenFone 2 models run on Intel Atom quad core, 64 bit CPUs with PowerVR G6430 graphics. The $199 model has the 1.8 GHz Intel Z3660 while the $299 model has the 2.3 GHz Intel Z3580. These are fast CPUs, particularly the 2.3 GHz that earned a spot in the top 5 in Android phones on several benchmarks. Though the Asus is half the price of US carrier flagship Android phones, it doesn't cut corners on performance. The 1.8 GHz model has 2 gigs of LPDDR3 RAM and 16 gigs of storage. The 2.3 GHz model has 4 gigs of dual channel RAM. Dual channel RAM allows for faster speeds, and is something we've seen in laptops and desktops but not phones. In fact, this is one of the first smartphones to have 4 gigs of RAM (a 64 bit CPU is required to address 4 gigs or more of RAM). The high-end model has a generous 64 gigs of storage, which is again unusual for a phone at this price. There's a microSD card for storage expansion, and the phone and Android 5.0 Lollipop support moving some apps to SD cards, though we suggest using a card for photos, videos and other documents.
A few years back when Intel Android products hit the market, neither the OS nor apps supported that CPU family well. We saw occasional lag and slower games performance. After 2 years of Intel Atom Android tablets, things have improved mightily and the Asus ZenFone 2 ran as smoothly and quickly as any Qualcomm Snapdragon phone on the market rated at similar speeds.
Front cameras are getting a resolution bump thanks to the selfie craze, and the ZenFone 2 is no exception with its 5MP front camera for photos and video chat. It can capture 1080p video, and provided reasonably bright and detailed photos. The real star is the rear 13MP camera, not because it uses the most expensive sensor or has super high resolution, but because it takes very good photos and video and the software rocks. Asus has a large team of software engineers thanks to their strong PC business, and they've done a wonderful job of creating a variety of useful features and effects here. The rear camera uses a Toshiba sensor rather than the more oft lauded Sony sensor, but Asus shows us it's capable of quality imaging. Stability is one thing you won't get at this price, so hold the phone steady when shooting photos and video--there's no OIS (optical image stabilization) as you'd find on the latest high priced phones. The rear camera tops out at 1080p 60 fps recording, another concession to the low price. As a consolation, there's a software video stabilization option to reduce excessive jumpiness.
Software effects are easy to understand since they're presented as thumbnails to illustrate the available effect. These include Depth of Field (background defocus or fake bokeh that's only modestly effective), HDR, a low light mode that combines sensor pixels to create larger virtual sensor sites, Beautification (it does a superb job of wrinkle and zit removal), GIF animation, panorama, Time Lapse and Time Rewind. There's also a manual mode for those who prefer to tinker with settings.
Software
The phone ships with Android 5.0 Lollipop, not the outdated Android versions we see on many price-conscious unlocked phones from importers. Asus has a huge team of engineers and they're proud of it. I honestly wish they'd stuck to the camera software and not thrown so many at the bloat added to the ZenFone 2. Older Asus smartphones and tablets had a pleasingly clean Android experience, but with the ZenFone 2 there's so much custom software that it boggles the mind. Custom versions of calendar, contacts, music and so much more abound (they're not offensive customizations, at least), and there are some useful items like the file manager, FM radio, a theming engine with some decent free downloadable themes, a backup app, Kids Mode and SuperNote. Others like the Photo Collage app, Party Link and myriad 3rd party apps including Clean Master, Dr. Safety, Trip Advisor, Kindle, Zinio and JawBone Up are just too much. It's as bloaty as a carrier-branded Samsung phone of old. And most of the apps are permanently installed in ROM so you can disable them but not remove them (unless you wish to root your phone).
Battery Life
So far, Intel CPUs haven't been at the apex of long battery life, nor have they been absolute energy hogs. In our experience, they're a bit behind Qualcomm for battery life, but ahead of NVIDIA Tegra CPUs. The 3,000 mAh battery that's sealed inside is par for the course among big phones, and we're thrilled that it supports Intel's flavor of quick charging. In fact it works with Qualcomm quick chargers too, and you get a quick charger in the box. Battery life on both the 1.8 GHz and 2.3 GHz models we have in for review has been OK but by no means stellar. The 1.8 GHz sips a bit less power, and both generally made it from 7am to 7pm with moderate to heavier than moderate use before hitting the 15% mark. 3D games like Real Racing 3 and even The Walking Dead drain the battery quickly since the phone also has to power a big 5.5" display (albeit at 1080p rather than QHD). In contrast, our LG G4 routinely makes it to 11pm before hitting the charger.
Conclusion
Thank you, Asus! In the US we have very few unlocked quality smartphones with 4G LTE that appeal to those who want and can afford something more than low end Moto and Lumia phones. The Asus ZenFone 2 is less than half the price of today's flagships, and you certainly don't have to settle for half the quality or features. The 5.5" IPS full HD display, fast Intel CPUs, good cameras and good call quality compete with the big boys, and the 4 gigs of RAM and 64 gigs of storage go beyond what most flagships offer. The looks aren't bad, the phone feels good in hand and our only concern is slightly weaker than average LTE reception.
