I have 5-6 BT watches, this is the best. Comfort to wear, light weight, strong vibration, water proof (they said can wear it for swimming but not diving). The battery last for a week (always on), the display is e-ink so it's always on and the backlight can be turn on by swing it. Clock works independently, it will sync with the phone if connected. BT connection seems quite stable.
Also there are many developers writing apps for android (phone) and the watch itself.
more or less the same, but Gear have camera and it can act as a hand free too. for me BT watch just need to alert me anything from the phone specially when someone calls. and the most important spec for me is the battery life, i read somewhere that Gear only last for one day (thanks to the colorful display I guess) ...... and its more bulky than the Pebble.