"Amazingly good."
I have had the robot a couple of months now and love it. It copes with wooden and stone floors well and I am always amazed by how much dirt it collects when on a seemingly fairly clean short piled woollen carpet. Don't get me wrong you will still need to hang on to a 'proper' vac because there will always be stairs/small areas that it doesn't fit but for a general everyday clean up it is brilliant. I would imagine it would be a boon for elderly/disabled people who can't manage a heavy vac but want good results from a lightweight. Even the dog has stopped being terrified of it!