Doesn't hold a charge over time.  Don't buy.
The buttons are poorly designed and it is easy to accidentally change the speed, but I could work with that.  After about 4 months it stopped charging.  I made sure the outlet worked, made sure to plug it in firmly, gave it lots of time to charge and within the next month it wouldn't even hold enough charge to get thru 1 use.  It if basically an expensive piece of garbage now.  Such a disappointment.
Rating: 2 stars