Surface RT selling modestly due to limited distribution and poor reviews for RT itself.
The hardware seems solid (I finally tried one tonight with both covers), but popping into the Desktop ruins the experience for people who only want Metro. (Me, I want full Win 8, so it matters a bit less to me... but breaking the Metro experience is still jarring.)
OTOH, although I've heard of Metro app numbers increasing, there's clearly a lonnnng way yet to go for it.
If all this is being pinned on Sinofsky, it's very short-sighted on Ballmer's part. With the legacy restrictions he had to deal with, I think Sinfosky did a very good job for a 1.0 product and the promise is there.