T.S.
I have a Fitbit One.
I like it. I wear it clipped onto my undershirt (I don't wear a bra generally... I know, I'm a weirdo).
I like that I don't have to swing my arms for it to know I'm moving.
It syncs via bluetooth with both my phone (windows phone) and laptop, which I like. I use the vibrating alarm in the morning and it has TOTALLY CHANGED the way my morning starts... it's so much nicer to be gently buzzed awake than to hear a screeching alarm startle me out of sleep!
I like that it tracks my sleep as well.
I didn't pay for mine directly... I chose it as a credit card reward, but I really like it and it was worth the "cost" of not getting something else.
I also like the program/app that runs with it that lets me set my goals and keeps me on track etc. I'm not trying to lose weight generally. I actually like it because it reminds me what I'm doing and when I SHOULD eat something or drink some water, and when I've had a lazy day and probably should say no to a big slice of cake!