I have a Nike Fuel Band and I am truly addicted to it... I find myself much more active these days just so I can earn more "fuel" and beat my previous "goals"... it tracks steps and calories and distance as well, but I'm really just interested in using it to be more active during my day... so I find myself walking more and taking the stairs more and things like that to make my fuel goal for the day...
Maybe it's a little bit gimmicky, but I still think it's pretty cool anyway... and it doesn't really matter much for me because I already use various HRM's and GPS to track my "real" training...
So for me I definitely find it pretty motivating and it has like I said really got me moving more during my day... but I still need the HMR's for my more specific goals when it comes to my running... and of course it just wouldn't be practical to wear a HRM and chest strap all day long anyway... not to mention that would be a bit much... even for me...