I've been using it since a day or two after it came out. Pretty decent, a reasonable improvement over Vista (which I rather dislike, though I still have it as the primary OS on one of my main systems). I can't say I'm a fan of the new taskbar or Start menu, and I hope they ultimately continue to allow some kind of "Classic" mode for both, but the customizability of the taskbar is nice at least. Performance also seems improved, as many others have said. All in all I think the biggest praise I can give to it at this point is that unlike Vista, once it is released I will not do everything possible to avoid getting a system with it installed. As it is now, almost 2 years after Vista release, I still quite often find myself opting for the "Windows XP Downgrade" option when purchasing machines. It will be nice not to have to pay the $99 additional! My last hope for it is that they rethink the number of different variations they offer. I really wish they would go 64 bit only, but I guess that will have to wait for Windows 8...
- Oshyan