No, I know the functions, but I still feel these things are gimmicks. You asked about this a few months back as well, and while it seems cool, I don't see how it's worth $100. I'll look into it more, but is there some conclusive evidence about its accuracy and stuff?
I ask this mainly looking at the sleep monitoring. There are thousands of dollars worth of machines that hospitals use to monitor patient sleep patterns, eye movements, and brain activity. How does a $130 device manage to do it for less? If you take that with a grain of salt, then shouldn't everything else the data tells you be the same?
For activity measuring, it's no different than a pedometer then. A pedometer and a cheap heart rate monitor for $130? I need to see more evidence. All the reviews I've seen so far are tech sites and they will obviously harp on the tech aspect of it, like how cool it is and its features, or lack thereof (wireless sync, etc.).
That's why I see it as a bit of a gimmick.
EDIT: In fact, without reading this article and going straight to the Verdict, it says exactly what I'm saying.
http://www.techradar.com/us/reviews/gadgets/jawbone-up-1145335/review
If you have $130 to blow on some questionable statistics, then go for it. It'll definitely be interesting. I don't think someone that serious about improving their lifestyle is going to take it too seriously, though. Otherwise doctors would be recommending this thing left and right to use in conjunction with their knowledge and noted patient progress