Some people have asked me, "why do you have one?" I really want to answer "because I can!" I really got it to track my sleep. Which after a week the device learned to do with a freaky amount of accuracy. It is not spot on, but it is very close. I also like the idle alert. You can set it to remind you if you have not got up and moved around for awhile. I have my idle alert set at the 60 minute mark. My job is mainly a desk job and I can get easily sucked into projects and lose track of time. When the idle alert goes off there is a little vibration reminding me to move!!! Sometimes I need that!
Currently I am waiting patiently for the replacement to arrive, while my broken one does the cha cha across my desk. For some unknown reason it is vibrating every so often. It was fully charged when the button broke, so i figure it has a few more days to dance on my desk.
People ask me if I would recommend it? Sure if you want to get a different view point on your activity level or sleep patterns it could help. However is it essential? Well not many "things" in life are essential.