The Xperia M4 Aqua boasts a slick exterior. It is quite thin and has that very distinctive Sony look.
There's no point in beating about the bush, the Xperia M4 Aqua is a spitting image of the Xperia Z3. Sony was quite obviously going for that quite-recognizable premium look of the flagship and there really shouldn't be any shame in this approach. Moreover, the M4 Aqua really pulls it off marvelously. One could easily mistake the couple at first glance, as even their dimension are almost exactly identical - 145.5 x 72.6 x 7.3 mm for the M4 Aqua, as opposed to 146 x 72 x 7.3 mm on the Z3.
The M4 has the same overall appearance, down to every corner and groove of the device. Build quality seems to be comparable as well. Everything on the M4 Aqua is nicely put together and fits snugly and it really has to, considering the IP68 dust and water proof certification.
Materials, however, differ greatly between the two devices, although Sony has managed to mask the differences incredibly well. Upon first contact you could easily be fooled that the M4 comes with a metal frame, like the Z3, but it is, in fact a very convincing polycarbonate. Actually, it looks and feels so good, that we can't really find any faults with it.
The back has also underwent a material substitution. Instead of the glass finish on the Xperia Z3, the M4 Aqua is adorned with an equally stylish plastic equivalent. It also looks almost identical and definitely gives the impression of glass. Sadly, it keeps just as many fingerprints as well. We did also notice a give when pushing down on the back of the device, but it is definitely nothing to worry about.
Other than that, Sony has really done the best it could with the available materials and add some. The body feels nice to the touch and the plastic does not look cheap in any way. The M4 Aqua comes in three colors - black, white and a pink one, called coral.
The Sony Xperia M4 Aqua is equipped with a 5.0-inch display, with a resolution of 720 x 1280 pixels. It has a pixel density of 294 ppi, which is slightly lower than the one on the Z3 Compact - 319 ppi and worlds away from the 424 ppi of the Z3. The bezels on the device are also quite big, but they are not bothersome, especially on a black unit. The smaller 5.0-inch screen in what is essentially a Z3-sized body leads to a screen-to-body ratio of about 65.2%.
Above the screen, the earpiece features a grill design, again similar to the Z3.
The 5MP front-facing camera is slightly off to the right. The phone does not feature any physical buttons, so the area below the display is mostly empty, except for the mouthpiece, which is identical in design to the earpiece.
Going round the device, we find the left side housing only a microUSB port and a flap to cover the microSD card slot. It is evident that Sony has applied some additional waterproof coating to the microUSB port, as it is sitting out in the open, without the need to be protected by an additional cover, like on the Z3, for example. This is significantly more convenient for charging and Sony guarantees that it is just as waterproof as its old solution.
The right-hand side is a little bit more-cluttered. At the top there is a flap. Covering the single or dual Nano-SIM slots. There is the signature round Power/Lock button, conveniently placed slightly above the middle of the device and, below it, a slim volume rocker. Near the bottom, there is a very thin and almost unnoticeable dedicated camera shutter button. It makes taking photos all that more-convenient - especially underwater where the capacitive touchscreen gets confused.
The 3.5mm headphone jack is placed on the top of the device near the right corner. Next to it is the secondary noise-canceling microphone.
The bottom of the Xperia M4 Aqua houses the main microphone and a speaker. They are spaced out as far as possible and shouldn't get in the way easily.
Around the back, we find a slick plastic finish, quite reminiscent of glass and equally prone to smudging. It houses only the 13MP main camera and a single LED flash.
Other than that, there is a Sony brand as well as an Xperia brand on the bottom and a little NFC logo. Actually, the back of the M4 Aqua is so similar to the one on the Z3 that it is almost indistinguishable. The only difference is the camera text on the Z3, but you really have to know what to look for to notice. Well, that and you can also probably spot the perfectly flat glass on the Z3. Under light, you can spot a slight unevenness of the Xperia M4 Aqua back surface.