Just posted this as an answer in the discussion forms, so thought I might as well add it as a review...
Yes I have this and its ok, can't really compare it to a silicone skin as I haven't tried one, but this is quite good. It hooks on to the bottom of your balance board using the two elastic straps underneath and it seems to hold quite well - there are little grooves near the board feet and the elastic fits in there.
I haven't really noticed any difference in the boards sensitivity either so that is a bonus. The ends of the mat can curl up a bit and it can feel a bit grippy at first but only while you are getting used to it. Its about 5-8 mm thick I would say and it has a kind of basket weave texture to it.
It stays put fairly well but that depends on the exercise you are doing, mine slips around a little bit during step aerobic, but that probably says more about my ability than anything else, and it is nothing that causes any hindrance really.
It does keep your board clean and it is worth it just for the fact that the balls of my feet don't ache as much after a workout!