Story to this is brilliant, on about chapter 9 now and am absolutely loving it. Every time I sit down to play it I end up on it for a few hours at a time! Story is good, music is good, graphics are mediochre at best, the AA is very poor, lots of jaggly edges, even on max, but the game is so good that I don't care. I can understand now why people were excited when it was released.
Am also looking forwards to playing the DLC when I am done. It's a much more immersive game than GTA4 ever was, in my opinion. The story is just miles better and a lot more interesting, especially with the whole 40s/50s vibe.