I'm most interested in seeing what the graphics performance and battery life is like. Hopefully neither one sucks too bad, although I'd gladly sacrifice some battery for better graphics capability. If these can really replace even a moderate laptop and have a decent battery life I may seriously consider one.
It'll also be interesting to see what other PC vendors come up with as a counter response.
By the way, in the press showing yesterday the demonstration Surface tablet they were using crashed, and they had to quickly swap it out for another one!