One of two new Google phones, the Nexus 5X is the smaller brother to the 
Nexus 6P, and one of the first to run 
Android 6.0 Marshmallow. It has quite a few upgrades compared to the 
Nexus 5, which arrived way back in 2013, and is also built by LG as Google's manufacturing partner. And as the 
LG G4 is now cheaper, it's one of the Nexus 5X's rivals.
Update April 2016: After living with the Nexus 
5X for five months, it remains a great option for those looking for a 
decent smartphone without breaking the bank. There's plenty of new 
competition such as the Galaxy S7, LG G5, Huawei P9 and HTC 10 but in 
reality, they're all much more expensive and - arguably - new 
competition for the Nexus 6P rather than the 5X.
An unlikely rival to the Nexus 5X is the new iPhone SE
 which is the cheapest phone Apple has launched in a long time at £359. 
That's still £60 more expensive, though: Google has dropped the price 
from £339 to £299, and is still offering outstanding value for money.
A software update a while ago did cause some performance issues 
and at times the lag has been very frustrating. However, Google has 
promised to sort this out with anoter firmware update. Otherwise we've 
had no problems and really enjoyed using the Nexus 5X.
At launch, the Nexus 5X had lots of rivals, including the 
Moto X Play, and the cheaper
 OnePlus 2.
 It's great phone overall, with one of the best 1080p screens we've seen
 to date, along with one of the best cameras. But it's not all great 
news. This isn't just a Nexus 6P with a smaller screen: the 5X has a 
slower processor, which means it lacks some of the shooting modes you 
get on the 6P and - for some reason - Google thinks people won't want 
any more than 32GB of storage. And the base 16GB model really doesn't 
have enough usable storage for a phone that records 4K video which uses 
up 300MB per minute.
But instead of dwelling on the negatives, let's get into the detail as there's lots to like about the 5X.
Google Nexus 5X review: Price and competition
The Nexus 5X costs
 £299 from the Google Play Store
 as well as from other retailers and mobile operators on contract. 
That's a reasonable amount cheaper than the Nexus 6P which starts at 
£449 (this hasn't had a price drop). 
See also: 
20 best Android phones to buy right now
Although
 it's relatively affordable, there's tough competition. Aside from 
Apple's 'cheap' iPhone the OnePlus 2 (with its more powerful processor 
and more RAM) is £239 and the Motorola Moto X Play is £279. Gone are the
 days when the Nexus flagship was simply the best-value phone on the 
market bar none.
 
 
Design and build
Google Nexus 5X review: Design and build
Despite
 an increase in screen size from 5 to 5.2in, the Nexus 5X is still nice 
and light. It weighs a comfortable 136g, and is 7.9mm thick. It is 
larger than the 5, though, so anyone hoping for a bigger screen in a 
phone the same size will be disappointed. Here’s how they compare:
- Nexus 5: 138 x 69 x 8.6mm, 130g
- Nexus 5X: 147 x 73 x 7.9mm, 136g
 
Rounded
 edges on the rear panel make the Nexus 5X a nice phone to hold in the 
hand and we like the matt finish plastic which is similar to the 
original. There’s a choice of colours including Black, White and Ice 
Blue, although this applies only to the back: they’re all black on the 
sides and front.
There's not a lot else to say on the design front
 as the device, like the Nexus 5, is fairly plain. That's a good thing 
we'd say although features such as waterproofing wouldn't go amiss. One 
thing to note: despite appearances, the 5X does not have stereo 
speakers. The top grille hides a speaker that’s used for phonecalls, 
with only the bottom one being a loudspeaker.
Another thing to 
point out is that the camera does stick out a little bit at the back. 
It’s now positioned centrally and although the Nexus 5's camera wasn't 
flush the 5X’s protrudes much more.
If you're wondering about the circle below the camera, it's a fingerprint scanner which we'll talk in more depth below.
You
 may also be interested in the fact that the Nexus 5X takes a nano-SIM 
rather than micro which may require a new SIM card if upgrading from the
 Nexus 5.
 
Hardware and specs
Google Nexus 5X review: Hardware and specs
Given
 that the Nexus 5 launched two years ago, it’s no surprise that the 5X 
is upgraded in almost every area. But don't expect it to blow its 
predecessor out of the water because the top-end hardware has been 
reserved for the Nexus 6P.
Google has decided to stick with a Full
 HD screen resolution on the Nexus 5X.  This of course means a small 
drop in pixel density to 424ppi. It’s not noticeable of course, and the 
screen is still crisp with pixels that are invisible to virtually all 
human eyes. But if you want an upgrade to Quad HD, you’ll have to look 
at the Nexus 6P – or elsewhere.
Staying with the display, the 5X 
has an IPS LCD panel just like the Nexus 5, but unlike the 6P which uses
 AMOLED. However, this is no criticism. The 5X has unquestionably one of
 the best screens we’ve seen on a smartphone. Sure, colours don’t 
assault your eyeballs as they do on the 6P, but they’re accurate and the
 screen is bright and has excellent contrast.
 
There’s
 an uprated Qualcomm processor too. The Snapdragon 808, as used in the 
flagship LG G4, is a nice upgrade from the 800 model which was 
top-of-the-line when the Nexus 5 arrived.
This means the Nexus 5X 
has a six-core processor with four A53 cores at 1.4GHz and two A57 cores
 at 1.8GHz. There's also Adreno 418 graphics which performed well in our
 tests – better than the Nexus 6P’s Adreno 430 in fact. (This is due to 
the fact the 6P has more pixels – it’s more powerful if you run the 
benchmarks at 1920x1080.)
Despite rumours suggesting the 5X would have 4GB of RAM, the allocation remains at 2GB.
And
 storage options are more limited than the 6P. The Nexus 5X doesn't 
offer 64GB or 128GB as the 6P does, instead there are merely 16- and 
32GB options. And as usual with Nexus phones, there’s no microSD card 
slot so you'll probably want to go for 32GB which costs £379.
One 
of several features shared between the two new phones is the fingerprint
 scanner: Nexus Imprint. It's positioned below the camera at the rear of
 the phone. It might seem a little strange, but it’s where your index 
finger naturally lies.
 
It's
 also super-fast and unlocks the phone almost instantly. The system 
learns your fingerprint and recognition improves over time. As well as 
offering easy access to the phone, other apps can use the sensor for 
logging in or making payments. Plus, of course, Google Pay will be 
coming to the UK at some point so you’ll be able to pay with your phone 
in bricks and mortar stores as you can with an iPhone.
The next 
shared feature is a new physical port in the form of USB-C which is fast
 becoming the standard for new Android phones: it can also be found on 
the OnePlus 2 and the Xiaomi Mi4C (which, incidentally has very similar 
specs to the 5X for half the price).
USB-C’s main feature is that 
it's reversible but it also enables fast charging and you can even 
charge other devices from the 5X should you wish to.
The larger 
frame means a larger battery at 2700mAh, but it's a big shame there’s no
 wireless charging: that’s a step backwards from the Nexus 5 and a blow 
for many looking to the 5X as the definitive upgrade.
Elsewhere 
there’s dual-band 11ac Wi-Fi, LTE (both faster than before), NFC and 
Bluetooth 4.2 but no infrared port or extras such as a heart rate 
monitor.
 
Cameras
Google Nexus 5X review: Cameras
 
The
 last of the shared upgrades between the 5X and 6P are the cameras. 
Arguably, this is the biggest upgrade for the Nexus 5X. The Nexus 5's 
8Mp camera wasn't amazing, even with the software updates which improved
 things following its launch.
But amazing is an adjective which 
will be used repeatedly for the 5X's main camera. It's one of the best 
cameras on any phone and as far as we can tell is identical to the unit 
on the 6P.
The new camera is not only higher resolution -12.3Mp - 
but has a dual-tone LED flash, an IR laser focusing system and can shoot
 4K video. There are phones with more megapixels, but the larger size of
 the sensor and pixels means more light hits them. The improvement in 
quality is obvious from the photos, but it performs well not only in 
good light: it's also pretty good in dim conditions too.
In photos
 and videos colours are rich and detail is sharp. As we said in our 
review of the 6P, there's possibly a little too much sharpening going 
on. But most people will be over the moon with this level of quality 
from a £339 phone.
It's worth noting that you need to use the HDR+
 mode most of the time to get the best quality and this does introduce a
 second or so delay of processing between images. You can shoot without 
it, but skies tend to blow out even when the contrast to the foreground 
doesn't appear that high.
The other gripe is the absence of a 
1080p60 mode: you can shoot video only at 30fps in 4K or 1080p. That's 
something which we hoped would be added in a software update, but it 
hasn't happened.
 
This is a 100 percent crop:

Macro perfornance is identical to the Nexus 6P:

Again, the 100 percent crop of the original photo:
 
 
Nexus 5X vs 6P camera features
Nexus 5X vs 6P camera features
What
 won't be added is a 240fps slo-mo option, nor SmartBurst. Both are 
features you get with the 6P. The Snapdragon 808 isn't quick enough to 
handle the way Google has implemented these features, so you're limited 
to 120fps at 720p. It's a shame, but won't be a dealbreaker for 
everyone.
More of a disappointment is that the 5X doesn't even 
have electronic image stabilisation, let alone optical. That means both 
new Nexus' lack OIS and you'll have to have steady hands if you want 
shake-free video and blur-free low-light photos from your 5X.
At the front is a nice upgrade to a 5Mp selfie camera. Again, it's the same as the 6P's which means decent quality photos.
Performance and battery life
Google Nexus 5X review: Performance and battery life
We
 already know that the Snapdragon 808 isn't as quick as the 810 in the 
6P, and that it has only 2GB of RAM versus the 6P's 3GB (and it's a 
similar story with the OnePlus 2, which is much cheaper than both Nexus 
phones).  The graphs below show the difference in our benchmarks, but 
again, it's important to note that the lower screen resolution explains 
why the 5X's frame rates are higher in GFXbench.
In
 general use, the 5X feels very quick whether you're playing games, 
switching between apps, browsing the web or just navigating around 
Marshmallow.
Battery life is very good, too, lasting a shade under
 7 hours in our tests. The new battery saving features in Marshmallow 
will also help if you need to eke out several hours when power is 
running low.
And there's support for fast charging using the 
included charger, giving up to 7 hours of use from 10 minutes' charging -
 according to Google. But it's not Qualcomm Quick Charge 2.0 or 3.0. 
Like the Nexus 6P, it seems to be a proprietary system, so you'll need 
the official charger or a third-party USB-C charger that can output 
5V/3A.
Software
Google Nexus 5X review: Software
 
Out
 of the box the phone runs Android 6.0 Marshmallow. It's similar to 
Lollipop but isn't exclusive to the 5X or 6P of course. Existing Nexus 
devices will be upgraded shortly, including the Nexus 5.
The 
benefit, as with any Nexus phone or tablet, is that you get pure Android
 as Google intends it to be – no add on skins like Samsung's TouchWiz or
 HTC's Sense.
Not only does it offer something of a blank canvas 
with which to customise Android to your heart's content, it means you 
don't have to worry about things like pre-installed apps which you may 
not be able to delete.
 
Don't forget to check out our 
10 best Android Marshmallow features article.