So far I have had very little experience with Windows 8, only a look at a beta version that a friend of mine chose to download and test. It looks sleek and is very responsive, especially as it is largely based on Windows 7. However there is a big concern about something called SmartScreen that allegedly send back information to Microsoft about everything you install. There are several aricles on Google about this.
Personally I would wait and see what happens. Windows 7 is very reliable and fast, rather like XP, and that is the OS I am staying with for now.