I got to admit I am interested. What they are trying to do is what Apple has been trying to do, but it look like Microsoft might beat them in the single platform game.
A supposedly inside rumor has it that there is a potentially enormous compatibility issue with ancient software, which might check for Windows versions starting with a "9" and decide it was running on Windows95 or 98 and halt. Seems implausible to me, but maybe.
Anyhow, I'm downloading the preview right now, but I haven't identified a guinea pig as yet.