Bethesda Rocks!
First off I noticed it is highly customizable (as far as your main character's sex, face, hair and race go). Not like Oblivion, which kind of saddened me; but quite a bit more than any other game. Note to game developers: We love looking at ourselves! And character customization only sweetens that vice. I do not know why more developers catch on to this fact.
The game is beautifully rendered. Being a longtime Bethesda (or Bethsoft) fan, it took me a while to get used to the bleak grays and washed out yellows and greens of this game. The colors are realistic more than vibrant, but once I adjusted to it, I noticed the game really is one of the best rendered ever. This does lead to my only criticism of the game: the gore content. Body parts are strung out everywhere, you can eat corpses, you can sleep in beds with dead bodies, heads exploded like a ripe tomato when you shoot them or simply come unattached and lie around for days. It is without a doubt one of the most visceral games I ever played, so be prepared. A gore setting would have been ideal for this game as my 13 year old nephew is chomping at the bit to play it, but I have no intention of letting that happen. I can't even let him watch me play for 5 minutes because the gore is so ever present.
The storyline is secondary. It was well written although a little thin and way too short. The characters could have been fleshed out a lot more as they are also a bit unsubstantial, especially compared to Bethesda's Elder Scrolls series. I did find some of their characteristics like speech and movement tics interesting and fresh. A valiant effort and a good sight better than most, but all games need to work on this particular aspect of the game. I expected a bit more from Bethesda as this is kind of their "thang", but I recognize that they are working within the constraints of an already established franchise. The story is, however, engaging and well played.
The gameplay is amazing. "Highly Addictive" is the coined phrase. I played every quest I could find. I played the game twice and then started a third time. Replay value is high as you can play as "good", "evil" or anything in between. It all ended too quickly and abruptly, which was a surprise. I won't give away the ending, but it was not satisfying for me at least.
Overall, I would have to say this has got to be one the best games ever produced, definitely the a game of the year candidate.