Check out the Fitbit forums before buying.  See how they handle a poorly designed product.
The first one I had failed and it was replaced.  The issue now is that if you have a Comcast internet account, it no longer works.  Apparently it was designed with antique wi-fi technology.  The solution is to reset your wi-fi settings after a Comcast update.  For me, this is daily.  If you read the responses from the Fitbit on their help forums, they border on rude.  The basic theme is that they acknowledge the issue but their proposed solution is to purchase the new Aria 2.  I for one am not spending another dime on Fitbit equipment.
Rating: 1 stars