Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
This game has one of the best story lines I've ever seen, and it's that which gives it a good mark.
It's a fun game to play, with a strange lack of violence, dispite the guy being stabbed every six seconds... But the best part is that it has many different sotrylines, it's spooky in certain places and the voice acting is convincing. It looks stunning for the time and as an added bonus, you can skip some of the annoying cut scenes after you view them, so happy days.
The only bad thing, is that it can be too repetitive, but hey, nothings perfect.