Downloaded it to my 2GHz AMD Athlon64 running 1Gb RAM and Vista.
It actually runs very well. Installation was perfect - no glitches even when it updated my DirectX instance automatically. The interface is different, but quite comprehensive - smooth-as and actually very slick. Pretty good for a first effort and way better than Google Sky. ASCOM telescope control, location-based real-time views. Pretty quick and no more than 20Mb to download the core engine and basic graphics set.
I'm finding it entertaining to watch people complain about MS at every chance they get because they feel they must. Go boys!
It's evident that there's a mind-boggling amount of work in this, and I can't quite understand people's dismissive treatment of it just because Microsoft Research funds it. Give 'em a break boys - they've recognised astronomers for once and are spending money on us. I, for one, applaud their effort.
It murders Stellarium I gotta say.