Why you can trust TechRadar
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…
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