I just got one last week for a challenge at work.
What do you want it for?
I find it interesting to see how many miles I walk during the normal course of my day.
However, I don't know that it's entirely accurate. I ran 10 miles yesterday (per my GPS, which is quite accurate) and my fitbit flex said it was only 9.1 miles.
It also doesn't track other activity level (like when I bike or do yoga.)
It's also interesting to see what it says about sleep -- it shows me a graph of when I wake up during the night, etc.
It's hard to know if it's worth the $100 for you without knowing your financial situation (will you have to give something up for it?) and what you're trying to do with it.
If money is tight and you're trying to lose weight, I'd say the money would be much better spent buying some free weights and the book "New Rules of Lifting for Women."
But if money's not an issue and you're looking for some kind of motivation and/or are just curious about things, I think it's worth it. I'm glad I bought one.Me: BW, divorced, now fabulous and happy!
Married: 11 years, no kids
The greater danger for most of us lies not in setting our aim too high and falling short; but in setting our aim too low, and achieving our mark. -Michelangelo