Wildly inconsistent!!
This is definitely the most frustrating scale I've ever owned.  Conceptually, I love it.  In practice, the scale never reads even remotely consistently.  I've tried repositioning the scale to different floor surfaces (tile, hardwood, etc), I've tried resetting and recalibrating it... nothing helps.  On multiple occasions, I've weighed myself 6 or 7 times in a row, only to get readings on both weight and body fat that fluctuated over 11 pounds.  11 pounds!!  I'm going to contact FitBit and see about a replacement; perhaps the unit is faulty.
Rating: 2 stars