I think the aspirations behind the Surface Pro are solid, but everything I've read about the execution leads me to believe that it is a huge failure. That happens. Sometimes you try to push something too early or it requires many iterations to actually get right. I suspect it will take a lot of evolution for some frankensteinian relative of both mobile and desktop operating systems to be good enough to actually serve as the root of the future of personal computing. I'm certain that Windows 8 and the Surface Pro won't be anything more than a footnote in that evolutionary tree.
In many ways this was pretty close to the move that Microsoft needed to make now, but it's not right enough and not good enough and not executed well enough either. In the timespan between the announcement and release Apple will have gone through an entire ipad rev. cycle. You can't fight against an OODA loop that is multiples faster than yours with half-measures and mediocrity. The company is already on the betting table whether you like it or not, you need to play to win or go home.