I have seen many reviews and gameplay-movies from the game Fallout 3 and I think it looks amazing..
I already have Oblivion, and Fallout 3 is kind of like that, but with guns, hacking, weird humor, VATS, zombies and other stuff.
I will probably buy it next Friday, because I have my Biology exam Thursday and I am afraid I might not be able to rehearse it if I have Fallout 3 :P