When my tablet was new, its battery used to last four to seven hours—depending on what you did. If you only browsed websites and chatted, the charge would stay there for an extremely long time. If you watched movies, listened to music, made video calls, and things like that, then it would still last, but not for that many hours. :b
To be honest, I despise Windows 8. When buying my laptop, the salesman gave me an offer to install that OS for few extra bucks… thank god I didn't accept it, haha. Would've been pretty frustrated if I did. I know that would have gotten used to it eventually, but still. In my opinion, they didn't need to implement all those tablet-like features into Windows 8. All that were needed was a new interface and some security improvements.