There are some obvious downsides to the UP, like having to move your arms in order to get the step recording for one. However I'm liking it so far - the smart alarm function is pretty nifty. I guess I could use a snooze function added to the alarm but I'm sure things could be added on the software/firmware side of things in the future.
The App isn't the smoothest app I've used, but for me at least, it does everything I need/want it to do - recording general activity and alarm. If you happen to buy it from Best Buy you could always return it in...I think 30 days
*It also has a power nap function apparently that wakes you up in 30 mins - Push Push Push+Hold (blinking moon), which isn't documented but seems to be working.