I'm not entirely sure where Microsoft is going with Windows 8, except that they've finally heard some of the complaints about bloat and have begun doing something about it. Even with all of the additional debug code that comes with early previews, it installs at a much smaller size than did Windows 7 (IIRC, 8GB vs. 14GB). This suggests that Redmond understands the limitations of the devices on which it might be installed.
That they're also going the Apple route (in a way) and using the same basic codebase for all platforms is potentially a good thing. It allows them to roll out new features on a more rapid basis and to fix vulnerabilities earlier than they traditionally did on WM5/6 (which is to say, almost never).
I'm not terribly excited over Windows 8 in the way that I was about Vista and 7. I don't see Windows 8 as nearly as much of a game changer. We're running 64-bit versions as a matter of course now. That move came more smoothly than I'd expected. The IP stack covers IPv6 pretty well, so once the ISPs get off their asses and start rolling that out, most people will be in good shape. (That reminds me that I need to re-enable it at home.) The video architecture isn't going to change up much, either. I don't foresee a mass rush just because of DirectX 12 or video playback; too many people have bought new systems that cover their needs under Windows 7.
I'll probably upgrade to it in part because that's what I do, and I applaud Microsoft for being willing to overhaul the UI in a more drastic way than anything since the Windows 3.1-95 transition. I'm just not convinced that it's ultimately that big a deal.
If I show up at your door, chances are you did something to bring me there.