(Pocket-lint) - The Sony Xperia M4 Aqua is one of the first waterproof smartphones to offer exposed ports, meaning no faffing around removing a flap to reveal the Micro-USB charging port. That, along with its flagship-mimicking design, saw this mid-ranger greeted with plenty of enthusiasm when it was first shown at Mobile World Congress.

The mid-range smartphone market is booming at the moment, but it's full of tough competition such as the slightly cheaper Motorola Moto G (third-gen), in among some flops, such as the LG G4c.

We have been living with the Xperia M4 Aqua for a few weeks to see whether its waterproofing and attractive design brings enough oomph to stand out in among the mayhem of the mid-rangers.

The Sony Xperia M4 Aqua's beautiful design serves as one of its best qualities, following the same OmniBalance style that Sony's flagship smartphones are associated with, such as the Z3+ (which, due to overheating, is not so hot).

Credit where credit is due: Sony has done a great job of making what is essentially a plastic handset look anything but plastic. The M4 Aqua benefits from the properties of such materials too, weighing 138g, making it lovely and light.

At first glance you'd be hard placed to notice the difference between Z3+ and M4 Aqua, as both feature the same curved sides, protected corners, side power button and dedicated camera button. The Micro-USB port is on the top left-hand side for the M4 Aqua, which is a slightly odd position compared to the bottom middle of the Z3+. Still, we're grateful that it isn't covered like it has been on previous Xperia devices. On the M4 there's a single speaker at the bottom right, which isn't as powerful as front-facing speakers; not much good for a party, but it's ok for watching the odd video.

It's only when you pick up M4 Aqua that you'll notice the plastic rather than aluminium frame and the plastic rather than glass rear. We had the coral colour model in for review and it looks fantastic - we love the metallic finish and how it gives a more premium appeal. Plastic is often partial to picking up the odd scratch, though, but this colour seemed to bat them off pretty well; be mindful that if you opt for the black finish then scratches are likely to be more obvious.

At this price point the M4 Aqua's waterproofing feature definitely stands out. Although Motorola has introduced water-resistance in the third-gen Moto G, it can't handle a full submerging. The Sony offers the same IP65 and IP68 ratings as the Xperia Z3+, meaning you can submerge it up to a metre underwater for 30 minutes and it'll continue to work. Take that, Moto.

The Sony Xperia M4 Aqua features a 5-inch 1280 x 720 resolution display, which delivers a pixel density of 294ppi. It's not the sharpest display out there, but this is the standard resolution at this price point.

As we said of the LG G4c, we don't have a problem with the resolution, per say, as it never leaves you squinting for more, but compared to a higher-resolution flagship device and, unsurprisingly, you'll notice a difference. The battery percentage and time displayed at the top of the screen, for example, aren't quite as crisp as they would be on a Full HD display - but that won't matter to most people.

Viewing angles aren't fantastic on the M4 Aqua and overall colours are muted with little punch, which is unusual given how vibrant Xperia's X-Reality displays tend to be. Whites aren't brilliant either, but this is more obvious when placed next to a display that does have brilliant whites. In isolation it isn't quite as noticeable.

We sat the Apple iPhone 6, new Motorola Moto G and the Xperia M4 Aqua next to each other for a quick comparison. The iPhone 6 delivers strong whites and deep blacks, as you would expect from a pricier phone, while the Moto G is very similar in terms of crispness to the M4 Aqua. However the Sony has a cool blue cast, whereas the Moto G has a warmer yellow cast.

Overall the M4 Aqua display is fine. It's not brilliant but it's not bad either, which is fitting of its mid-range position. We didn't have any issues with viewing the screen on bright days and it does offer white balance adjustment settings, which is a nice touch. There are also a couple of other clever features such as glove mode and smart backlight control, so for a mid-range handset it's hard to complain.

The Sony Xperia M4 Aqua comes with a 13-megapixel rear camera and a 5-megapixel front camera, which puts it in the same league as the new Motorola Moto G. Despite having 13-megapixels however, the M4 Aqua shoots in 8.6-megapixels on Superior Auto mode at a 16:9 ratio. It does better in daylight than it does in low-light, but that's pretty much a given for all smartphone cameras.

The colour balance is quite poor on the M4 Aqua however. Even in bright conditions there is an magenta cast on the majority of shots - and too much pink is never a good thing, ever. Some details in the shot above, such as the leaves have a pink shadow-like edging, which shouldn't be there - that's a case of fringing, as a result of poor optics.

When it comes to low-light shots, the M4 Aqua tends to use shutter speeds a little too slow for handheld shots. None of the images we took in low-light conditions were sharp as a result, but they aren't awful either. A lot of smartphones are programmed in such a way, so we won't lay into the M4 Aqua too much here.

Under the hood of the Sony Xperia M4 Aqua is the 64-bit octa-core Qualcomm Snapdragon 615 processor, supported by 2GB of RAM. Everything runs smoothly and in our use it's not had any issues switching between tasks and apps, which is great.

Storage is where the M4 Aqua lets itself down a little. There is 8GB on board, but you get less than 4GB on the device itself to actually fill due to the operating system install. However, there's microSD card support for storage expansion up to 128GB, which we'd certainly recommend using. This limited on-board storage isn't really an issue when it comes to videos and photos as the microSD can help out, but it is a problem if you want to download more than a couple of big gaming apps, for example, as these need to run on the core storage. Fewer Sony bloatware apps and a little more space would have been more welcome.

Battery life wins the M4 Aqua back a few points though. Sony is well known for offering decent battery life on its devices (Z3+ ignored) and the M4 Aqua is no different. We consistently got between one and two days of juice before we had to pop the phone on charge, depending on what we did or how busy our days were. You'd have to really go to town to not get at least a day out of the M4 Aqua - it isn't the kind of phone that will die on your train journey home each and every time.

In terms of software, the Xperia M4 Aqua runs on Android Lollipop with Sony's software reskin over the top. It has the all the usual apps we have come to expect from Sony's devices, such as Walkman, Movies, Video Unlimited, What's New, PlayStation and Xperia Lounge.

There is one thing that is noticeably missing and that's PS4 Remote Play, which is used for PlayStation 4 owners who want to play their games over network using their Xperia smartphone (or tablet) as a second screen. It's a unique feature to Sony's flagship range of smartphones so it would have been great to see it on the mid-range, but we understand why it isn't available given the power on board. Why would you buy a phone £300 more expensive if you can get the same features on the cheaper replica?

Everything else runs like pure Android would, you just have the Sony overlay on top with a few additional apps, like an Office suite. Despite us preferring a cleaner interface, the Sony skin is pleasant to look at and it delivers a good user experience overall. Any first-time phone user will be happy with it, as will more seasoned users.

Verdict We love the look of the M4 Aqua and how, despite being predominantly plastic, it offers much the same design as Sony's flagship Xperia devices. It's a charming smartphone, especially in the coral colour as reviewed here, which almost tricks you into thinking it's part of the flagship line thanks to its metallic coat of paint. It's not all just about looks either, with decent battery and solid performance outpacing its sub-£200 price tag - and much of the competition. However, the lack of internal storage, along with an average display and average camera do bring it down a peg or two. Overall the Sony Xperia M4 Aqua is a good mid-range smartphone, made even better by full waterproofing. That's one feature to make it standout in among the madness of the mid-range market, and therefore well worthy of consideration.

Writing by Britta O'Boyle.