Perhaps the coolest mode Rockstar is showing off with their new multiplayer trailer is the Gang Wars mode. Two teams fight there way through five chapters, each with different objectives. These conflicts drive a "dynamically shifting" story that is influenced by who comes out on top. Victories lead to advantages in the next round. Nice.
I also like the idea of Crews. Working like Squads in Battlefield games, players get extra experience for sticking together from match to match. Very briefly, the trailer mentions bonuses for sticking with your Crew across different games, but no other information is given. Damn you, voice over guy! I want to hear more about that. Wait, where are you going? Oh, you were just a voice on my computer. Okay, well. Bye.