Stunning. A masterpiece.
Visually, the game is beautiful. The music, sound effects and sound design is expertly executed and the game-play works on every level. It's a game that, despite the droll, grim context of the environment, you just want to spend time in. You want to wander around the Wasteland, running into roving gangs of raiders in need of killing or other restless wanderers in need of your help.
The karma system makes an interesting game even more interesting as you find that your decisions actually have an effect on the world and how those inside it perceive you.
I just can't wait for the downloadable content that will undoubtedly be coming in the near future, similar to how DLC was released for Bethesda's last offering, Elder Scrolls 4.
Regardless of what gaming platform you own(PC, X360, PS3), get this game, play this game, enjoy this game. You won't regret it.