Nuu Mobile X4

The Nuu Mobile is the latest low-cost Android firm to emerge from China, and it's aiming to take the affordable mobile market by storm with its first handset  - the Nuu Mobile X4.

The X4 offers a decent sounding spec list on paper (for the price) with a 5-inch 720p HD screen, quad-core processor, 16GB of storage and 13-megapixel rear camera.

You also get a removable 2,250mAh battery (something of a rarity these days), and it's all housed in a case which mixes plastic with premium-quality metal. 

The Nuu Mobile X4 is running an almost stock version of Google's Android 5.1 operating system, which is rather on the old side but still, it's so far, so good.

Nuu Mobile X4 price and release date

• Just £130, $170 SIM-free
• Available in UK and US

The Nuu Mobile X4 is the first handset from the firm to reach the UK, but it's also available wider in Europe and in the US.

SIM-free from Amazon you're looking at a Nuu Mobile X4 price of just £130 ($170) which sees it rub shoulders with the Moto G4, HTC Desire 530 and Wileyfox Swift.

Key features and design

• Design combines plastic with metal
• Quad-core power with 2GB RAM
• 5-inch 720p screen

The moment you pick up the Nuu X4 it's obvious where the phone's designers got their inspiration from – the handset is a dead ringer for the Samsung Galaxy Note 5, with its metal chassis and rounded sides.

While it doesn't quite match the build quality and overall desirability of Samsung's phone, it's a close imitation, and, slavish copying aside, there's little reason to feel short-changed from a purely aesthetic standpoint. 

The X4 looks good from practically every angle, which isn't something you can always say about budget Android handsets.

Metal runs around the edges of the device, which means your fingers are almost always in contact with it, and this lends the X4 a premium feel.

The back of the phone, however, is covered by a plastic panel. This snaps off to reveal a user-replaceable battery – something of a rarity these days – as well as dual microSIM slots and a microSD slot, which enables you to expand the phone's 16GB base storage.

Because of this pop-off panel, the X4 offers no protection against water or dust ingress, which shouldn't be all that shocking given the low cost of this phone.

Around the corners of the X4 you'll find the usual array of buttons and ports, but Nuu has made some strange choices here, the most obvious of which is putting the micro USB port at the top of the device, along with the 3.5mm headphone socket.

This means the bottom edge is reserved solely for the single loudspeaker and in-call microphone. On the right-hand side is the power button, while the volume rocker is positioned on the opposite edge.

Despite giving the impression that it has an edge-to-edge screen, the X4's 5-inch IPS display is surrounded by quite a large black bezel. Three capacitive buttons are located below the screen – back, home and multitasking – and there's no fingerprint scanner.

The screen has a HD resolution of 1280 x 720 pixels, which is perfectly acceptable in daily use so long as you don't look too closely – if you do, you'll notice that text can sometimes look jagged, and images aren't quite as sharp as they could be.

However, by far the most pressing issue with the screen isn't resolution, but overall quality; the display has a washed-out look which robs photos, movies and games of visual impact.

Interface and reliability

• Running old version of Android
• Low on bloatware and some unique features

The Nuu X4 follows in the footsteps of many other low-cost Android phones by using a relatively stock version of Google's OS. In this case it's Android 5.1, so the phone is a little behind the curve (Android 7.1 recently shipped alongside Google's Pixel phones) and we wouldn't hold our breath for the handset getting updated any time soon.

Having said that, 5.1 is still a pretty formidable platform, and comes with mod cons like Google Now and the battery-saving 'Doze' feature, which shuts off nonessential processes when the screen is asleep to conserve stamina.

While Nuu has left the core OS largely intact, and avoided the temptation to install loads of annoying bloatware applications on the X4, there are a few unique features which come baked into the software.

Because the phone packs NFC there's an alternative service for file transfer called HotKnot, which is apparently quite popular in the Far East. It permits the same kind of connectivity – file transfers, mobile payments and device pairing – but uses a special kind of capacitive touchscreen instead of a chip, as is the case with NFC.

Transfer speeds are slightly slower, but it's cheaper tech; sadly, you'll need another HotKnot-enabled device to use it, and those aren't very common outside of China.

Smart Wake, meanwhile, enables you to quickly start up particular applications when the phone is asleep with a range of touchscreen gestures; for example, double-tapping the screen will wake the phone, while drawing the letter 'C' on the display will open up the dialer.

While the gestures are set in stone it is possible to customise which applications they open, and once you become accustomed to it, this feature is actually quite a time-saver.

Air Gesture is another unique feature, and uses the phone's front-facing camera to detect your hand movements. It only works with two applications – the gallery app and FM radio – and basically involves you swiping in the air with your hand to scroll through photos or change the frequency of the radio.

It's quite a neat gimmick to begin, but offers little practical advantage over simply using your finger to swipe across the screen – plus it makes you look like you're trying to swat a non-existent fly half the time.

Movies, music and gaming

• Poor screen and sound for media
• Gaming performance decent for the price

The Nuu X4's washed-out 720p screen isn't the perfect platform for enjoying big-budget Hollywood action movies, while the phone's weak mono speaker means  soundtracks lack bass notes.

For music, the phone uses Google's own Play Music service rather than a custom audio player, which is fine as this links in directly with Google's iTunes-beating repository of tracks and albums. You'll want to use headphones to listen to songs, however, as that aforementioned speaker is very low quality.

Although the X4 is lacking in grunt, it actually did a decent job of running some pretty intense 3D games – something we'd guess is related to the choice to use a 720p display over a 1080p one.

Real Racing 3 runs at an acceptable pace, although when a lot of cars are on-screen it begins to drop frames and becomes a little jerky. Overall, the X4 isn't a bad gaming handset for the price, as long as you don't expect silky-smooth performance 100 percent of the time.

Specs and benchmark performance

• Basic, single-app tasks run smoothly enough
• Performance gets sluggish if pushed to any degree

The Nuu X4 has a MediaTek quad-core chipset clocked at 1.3GHz, backed by 2GB of RAM. This represents a slight improvement over the model which launched in North America earlier in the year, which only had 1GB of RAM, and suffered some near-crippling performance issues as a result.

But, while us lucky Europeans are getting a better overall package, what's on offer here isn't exactly at the cutting edge of smartphone processing power.

Basic tasks run smoothly enough – the MediaTek chipset is only having to push a 720p display, after all – but the X4 becomes noticeably sluggish when you're darting between processor-intensive apps, and there's a lot of background activity.

Applications that consume a lot of RAM cause the phone to freeze momentarily when you cycle between them, although casual users might not hit this particular roadblock. The X4 is perfectly competent at handling day-to-day activities such as surfing the web, email and listening to music, but you can't push it as you could a flagship device – but of course it doesn't have a flagship price tag.

AnTuTu Benchmark returns a score of 22733, while Geekbench 4 has the X4 pegged at 569 (single-core) and 1631 (multi-core). Compare that to the Moto G 4th Gen – which scores 46614, 719 and 3076 in the same tests – and it's clear that this isn't a heavyweight contender, even in the budget Android arena.

Chinese rivals like the Xiaomi Redmi 3 and Redmi Note 3 also comprehensively outgun the X4, despite costing around the same price.

Battery life

• User-replaceable 2250mAh battery
• Battery needs a daily charge with moderate use

The 2250mAh battery inside the Nuu X4 offers decidedly average stamina, despite the weak nature of the chipset and that 720p screen. A day of typical use left the phone gasping for air, and we had to charge it before bedtime most days.

On the plus side, the battery is user-replaceable, so you can carry around a spare if you need to – that's a feature fewer and fewer Android manufacturers are offering these days, so it's definitely a plus point.

During our standard TechRadar video test, which consists of playing a HD video clip is played for 90 minutes with the volume and screen brightness at maximum, and accounts syncing over Wi-Fi in the background, the X4 lost around 34% of its battery life.

Camera

• 13MP rear-facing and 5MP front-facing cameras both poor
• Video quality is no better than stills

The Nuu X4 comes with a 13-megapixel rear-facing camera and a 5-megapixel front-facing one, and neither is truly up the job of taking decent-quality shots. The main camera struggles when it comes to properly exposing an image, and is also frustratingly sluggish in terms of focus and capture time. 

The resultant photos are dull, lack vibrancy and – when you zoom in close – are packed with image noise. There's a HDR mode, but this adds a few more seconds to the capture time and doesn't really enrich images all that much, so we quickly stopped using it.

During our review period we didn't take a single snap we were totally happy with – the Nuu X4 is a very poor choice for mobile photography enthusiasts. The front-facing 5-megapixel camera is equally disappointing, but as long as you limit it to selfies and the odd video call, it's less of an issue.

The X4's main camera can capture video at 1080p, but the results are predictably poor, with the same complaints that apply to static images applying – footage lacks colour and life. The front-facing camera is limited to 720p recording.

Camera samples

Verdict

Once upon a time, any Android phone under £150 tended to get a free pass purely for offering smartphone functionality at such a low cost. But those days are long gone, and the budget sector of the market is now arguably just as cutthroat as the top-end.

With devices like the excellent Moto G4 and a stream of powerful, low-cost alternatives from China setting a high standard, there's little room for also-rans even in this price bracket – and sadly the Nuu X4 falls squarely into the also-ran category.

Almost everything about the phone is lacklustre compared to the competition. The 720p screen is unimpressive, the MediaTek chipset struggles under pressure, and the 13-megapixel camera frustrates every time you boot it up.

There's no fingerprint scanner or NFC – two features that appear on many other budget Android blowers – making the X4 a poor choice when compared to its rivals. 

On the plus side, a stock interface means no bloatware, but the X4 is likely to remain stranded on Android 5.1 for all eternity.

Why should you buy it?

If you're after a good-looking budget phone for basic tasks then the Nuu X4 might fit the bill, but more demanding users will quickly become frustrated with its shortcomings.

The eye-catching design is one advantage the X4 has over rival low-cost devices, and the fact you can replace the battery will be a big selling point for some. 

Should these be prime concerns as a buyer, then the X4 may be acceptable – but its faults make it hard to truly warm to.

Why shouldn't you buy it?

While the Nuu X4 does have some good points – the removable battery being perhaps the most notable, and the design is sure to turn heads – there are too many irksome issues to overlook.

A 720p screen isn't the end of the world, but the one used here is washed out and lacks punch, while the rear-facing camera is slow and produces disappointing snaps.

Being able to replace the battery is a plus, but the X4's average stamina almost makes this a necessity rather than a bonus – you'll need to have a spare in your pocket if you want to get more than 24 hours of use before connecting to the mains.

As we've been at pains to point out in this review, for most potential buyers there are better budget options than the Nuu X4 out there, and here are three of the best…

Moto G4

Arguably the king of the budget Android sector, the 4th-generation Moto G boasts a full HD screen and impressive power for the price, but like the Nuu X4 it lacks a fingerprint scanner and NFC support.

• Read our Moto G4 review

Wileyfox Swift 2 Plus

While it's a little more expensive than the Nuu X4, the Wileyfox Swift 2 Plus has a better design, more powerful hardware, and runs Android 6.0.1 as opposed to Android 5.1. It also has a fingerprint scanner and NFC, although the screen is just 720p.

• Read our Wileyfox Swift 2 Plus review

HTC Desire 530

The latest in the long-running Desire line has the trademark HTC good looks, but its Snapdragon 210 chipset is a bit feeble and it's lumbered with a 720p screen. It costs around the same price as the Nuu X4, so it's worth a look if you're strapped for cash.

• Read our HTC Desire 530 review