As good as any other game I've ever played. To all those who disagree because it's not like the original: nobody cares.
The game begins really strongly; It shows how well bethsheda has worked on the game and the amount of thought and effort that has gone into it. I felt immersed in the game right from the get-go which many games fail to do. I really liked the idea of beginning as a child and learning the ways of life while you--the player--learn the game simultaneously. Great concept and perfect execution.
Gameplay: Fantastic. Just plain fantastic. Great idea to allow the player the choice between first and third person. I played it as an FPS-RPG and I was not disappointed. The VATS system was excellent and given how your karma affects its effectiveness just makes all the more amazing. I thought the weapons were great. It was awesome--and sometimes frustrating--how sometimes even in heated battles how the guns would deteriorate and/or jam and force you to either choose another weapon or repair it before continuing on. There were so many other features that just made the gameplay brilliant but if I were to focus on that, this review would be too long.
Attention to detail: I just came up with this aspect because I felt it needed to be said. The attention to detail was freakin' unbelievable. I had read some previews recently about how Bethsheda focused on perfecting tiny segments of the game before moving onto the next portions just to make sure they got everything right. Perfection may be unachievable but striving for perfection is always worth it and this game is living proof of that.
Visuals: Absolutely great. Now, it's unfair that a game like crysis is used as the benchmark since their engine is clearly superior to all, but in all seriousness, with the exception of crysis and crysis warhead, fallout 3 DEFINITELY has the best visuals of any game I've ever played. The animations, aside from a few minor issues, is outstanding. From decapitating a super mutant in VATS to disseminating its remains all over the floor, the animation never ceased to impress me. Thumbs way up for this.
Story: Okay, now first off, let me say that this is the most subjective portion of the review (even more than gameplay). The fact is, I loved the story. The atmosphere was highly immersive and combined with the visuals, I just could not stop playing the game. I honestly don't know what else to say aside from the fact that it was truly great. The ending--regardless of your choices throughout the game--may be disconcerting to some, but I thought did not take away from the journey of the game. Love it or hate it, the story was still really well told.
Overall, I thought the game totally exceeded my expectations and I've spent the last couple of nights not even going to bed until 9 or 10 am just because I couldn't stop playing the game. THUMBS WAYYY UP!