As the name suggests, this is Sony's third smartwatch, but the first to use Google's Android Wear operating system.

The SmartWatch 3 isn't as stylish as certain circular smartwatches, but it's inoffensive. It has a square 1.6 inch screen and the only button is on the right. You'll rarely use it since the display lights up when you raise your arm or tap on the screen.

The main unit pops out of the strap so you can change colours, but at the moment there are only the official Sony straps which cost £20 each. They're made from rubber and have a sturdy buckle. It's easy to adjust for size without cutting.

Instead of wireless charging, there's a standard microUSB port. This means you can charge the watch almost anywhere as microUSB cables are plentiful.

The port is covered by a captive rubber bung which helps to make the Smartwatch 3 dust and water resistant. We wouldn't advise swimming with it, but you'll be ok in the shower or going for a run in the rain.

Sony SmartWatch 3: Screen and battery life

We found the battery lasted exactly two days, which is disappointing considering the transflective screen. This technology means the display is still readable without the backlight, and easily visible outdoors in bright light.

This efficiency means you have the option to keep the screen on all the time so you can glance at your wrist to check the time without having to tap or lift your arm. There's a built-in ambient light sensor which adjusts the backlight brightness according to how bright it is around you.

The display is roughly the same resolution as other Android Wear watches, but the disadvantage of using a transflective display is that viewing angles are terrible by today's standards.

If battery lasted 4-5 days we'd forgive this, but LG's G Watch R also lasts two days and its screen offers much better colours and viewing angles.

Sony SmartWatch 3: Features

The SmartWatch 3 does have one ace, though: built-in GPS. This means there's no need to take your smartphone with you on a run, hike or bike ride.

There's also NFC and Bluetooth. Bluetooth isn't just for connection to an Android smartphone: you can pair the SmartWatch 3 with some Bluetooth headphones and listen to music stored in the watch's 4GB of storage while on a run (such as the Mpow Petrel)

There's no heart-rate monitor, but the G Watch R only records heart rate on-demand rather than constantly. If you need continuous heart rate, consider the new Fitbit Charge HR or Surge.

The SmartWatch 3 won't track sleep or the number of stairs you climb, so it's not a serious activity tracker. What you can do is to install Android Wear apps, which add functions and features which could be even more useful. Right now the selection is rather thin on the ground, but it's sure to improve over time.

Sony SmartWatch 3: conclusion

The SmartWatch 3's biggest strength is its built-in GPS, but you'll still need a smartphone for most things, including driving directions.

The transflective screen is a good idea, but in practice battery life is no better than other smartwatches with better-looking screens. Ultimately, unless you're on a fixed budget, the G Watch R is the better choice. And if you can't afford that, just wait a few months as the price is bound to drop.

See also: the best smartwatches you can buy right now