Mutewatch is probably the most minimal watch out right now.
The watch at first just looks like a bracelet but with a tap it will wake up showing you the time. You can then swipe through the other functions of the watch which are the alarm and timer.
There is a built in accelerometer which registers your movements so it can adjust the vibration for notifications.
The watch will also last up to two weeks and takes two hours to fully charge from a USB port.
At the price of £179 it isn't cheap but I'd say it was worth the price tag.