Wear with Android 5.0, it's great. I use a Nexus 6, and everything works perfectly yet. I am pleasantly surprised by the size, which is smaller than what I thought. However, the fact of hardly find compatible bracelets is a hassle. Motorola smart to put 2 small pieces of plastic found to prevent us to change the bracelets with any 22mm wristband. It should therefore break to change the strap (which is feasible).
If not, be warned: the watch stays on for a few seconds before the screen turns off to conserve the battery. With the display always on, there would be no more than 2 hours of battery life.
We can use the watch to go running for example, without needing the phone. It will be able to give us the distance traveled, number of steps, your heart rate, etc.