Nuu Mobile X4 review

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.