I thought the trailer was awesome. The city seemed to have more life in it this time around. In the last trailer and in some of the screenshots we didn't see too many NPCs but it looks like there are plenty now. I love some of the damage modeling on the cars, looks better than IV. For example you see one of the trucks hit/crush a car and debris flies out everywhere.
I don't know if it was purely in cutscenes but when that one guy hops over the hood of the car and when the dog jumps on the car you see it sort of lower to the ground. That's an amazing level of interactivity. Also the way the clothes behave.. seems like Rockstar put so much detail into even the tiniest things and that's really going to make this game a lot better.