What a coincidence. I just bought the Fitbit Flex (basically the same thing) and so far I like it. it is a glorified pedometer but thats fine - anything helps. I chose the flex because its fully automated, wireless sync and no monthly website charges. The 'sleep recording' is cool. If I wake at 3AM, it shows on the bar graph report, not sure how they do that but its geeky and cool.
I recently started using myfitnesspal and I think it is neat that it can actually link up with it. Also find the wake up feature interesting. But I also wish it would measure heart rate and that it could link with my Garmin.