My parents have one. As far as i'm aware they haven't had any problems. and theirs goes from carpet to slate and back again without any issues. they just keep him docked, and then every now and again let him loose in a room and all done. It also knows to go back to the dock by its self if it is low on battery, and you can tell it different patterns to do or let it work out its own pattern. The only problem is they have chairs that have legs that go along the ground (itms), like a metal bar about an inch high that the poor little thing gets stuck on cause he tries to go over them... but just means mum puts the chairs out of the way when he does that room.