See, I saw the gameplay video tonight and thought, "I HAVE TO MAKE A POST ABOUT THIS!!" So I'll just write Ninja'd!
Love Rockstar lots. Love it more now. I'm seeing some Max Payne 3 in that shooting sequence, which is awesome because shooting in Max Payne was slick. Love the lighting in the drive at night scene. Also, the way the car handled looked significantly different to GTA IV, color me interested.
Regarding Multiplayer, when I played GTA IV, I had a tight group of players going on, and we'd create a server with RPGs only and no friendly fire. We'd shoot each others, which didn't cause damage, but flailed us around the map. Hilarity ensued all the time.
The general rule of thumb concerning multiplayer is: If you have good people to play it with, it will be fun no matter what. Another rule of thumb concerning multiplayer is: Don't play L4D with AI players.