Windows 8 is an incredible gaming OS as it runs much lighter than windows 7 does; it uses VERY little ram or system resources. That being said, it may have some compatibility issues with some programs (mostly older indie games). Also, if you're like a lot of the people on here who can't be bothered to think or take 5 minutes to customize the interface and would rather whine about change, you won't like the UI.
As long as you don't use metro apps and just treat it like windows 7 - i.e. go install chrome and use that as your browser, ect, then you'll do just fine. Windows 8 is a lighter windows 7 with a much better task manager and 8.1 also has much better search functions.