I cant wait!! I have it reserved, and lucky me the day it comes out I have the day off, and school at 7pm, so I have the whole day to play it! The gamestop near me is doing a midnight release, so me and a few buddies are gonna pick it up. Multiplayer looks to be amazing, I loved the one in SA even though it was very simple.
The only thing that I am dissapointed with so far is the lack of planes, and the lack of the wilderness. I loved the forest, mountain, and desert in SA. I had to have spent hours driving different cars up Mt. Chilliad to launch them off lol.
EDIT
YouTube - Grand Theft Auto IV FINAL Trailer
Check out at 38 seconds. I love how realistic the physics are of the guy being shot and rolling down the stairs.