At $200 this looks like great device with built-in sensors including GPS and UV that also talks to whatever phone you own. I also like the fact that heart rate monitor is always on. Addition of barometer could have been nicer, however.
Other tidbits:
-Screen looks too small to do much of an interaction so I'm guessing type of apps would be mostly notification types.
-I seriously hate all these stock photos and videos. Marketing seems to be out of ideas and creativity yet again. Show the f*ing product, not random faces.
-48 hr battery life
-Cortana works only for Windows Phone
-It's supposedly made for the right hand which is very weird.
-Sleep quality monitoring seems pretty cool
-The whole thing is projected as health device and makes me feel that it's designed for fitness nuts. This is going to severely limit the audience and very bad marketing strategy. Apple's watch is much more human/teens oriented that anyone wearing watches wouldn't mind to wear regardless of its health related features and probably mostly just for fun (send my heartbeat!).