Sony's Mobile World Congress hasn't been as busy as Samsung's or HTC's, which both just took the wraps off their respective flagship handsets for 2015. But alongside the Xperia Z4 Tablet, a powerful slate boasting an eye-catching display, the Japanese firm has also unleashed a new handset in the form of the Xperia M4 Aqua. While not as grandiose as the aforementioned efforts of rivals, the M4 is a waterproof, mid-range device that packs quite a punch, and with a design that looks every bit as slick as some of its top-tier Xperia Z3, it may well hit the sweet spot with the consumer market.