Our company gave each employee one for Christmas. 1st off, it only keeps track of calories burnt while moving. So basically if you have a desk job, prepare to look at your fuelband at the end of the day and see that you've only burnt 200 calories via your trips to the bathroom and lunch. Also, since it only calculates movement, it grossly underestimates calories burnt through weight training. Basically I came to the conclusion that it's really only useful to outdoor runners that have no means of tracking calories.. If you use the elliptical at the gym the heart rate monitor will accomplish the same thing. Oh yeah, it's also a solid band, not flexible like a watch strap, so it's awkward and difficult to hide under the cuff of a shirt..
Thumbs down imho unless you do all your exercise outdoors. I'd say 80% of the people at the office were no longer wearing theirs by week two.