I am updating all 3 of my computers to Win 8.
Running trials, they are significantly more responsive and smoother (multithreaded with older hardware is light years ahead), and there is nothing in it for games. Uses way less RAM too (less than 500MB with the complete UI and Superbar), so I can use more as a disk cache to make things even faster.
Unless you have specific legacy support requirements, there shouldn't be a reason to go backwards <:
I guess if you are old hat and still mainly use your mouse to navigate the desktop you wouldn't like Win 8, but if you've been using the super fast keyboard shortcuts for everything since Vista, it's a natural progression.