It is what I'd describe as a highly tactile rubber dome, but it's still got the bottoming out effect for sure.
Like I've said before, a worthwhile purchase if only to obtain a great box to transport other Model Ms, notably M13s as it has a spot to accommodate the trackpoint. The goodies it can be parted out for are just bonus. Case, if you don't mind a hole in the side, is a nice easy way to put a proper black case on a normal M.