Fitbit - Pros and Cons

I don't have a fitbit (yet anyway) but would like to hear why you purchased it, what you like about it, whether you would buy again, etc. I'm fairly active and do some serious power walking (sometimes a bit of jogging) and workouts on my elliptical.

Normally I just punch on my GPS and music and away I go so would like to know why I should invest in the fitbit. I currently do not track my steps during the day as I know I normally hit right around 8-10k without even trying and I do not track those steps in my MFP either.