They do seem to have addressed one of the main criticisms of the last game, which was that the world was empty. In the new one, they seem to have more random things going on as you pass by, like helping a bunch of rebels, GTA style.
Last night I was messing around, and at a checkpoint I got into a fight with some guards. During the fight I accidentally attached a guy to the front of a Jeep.
Then 10 minutes later, I saw a Jeep coming up the road, driving oddly, and when it passed, there was a guy stuck to the front of it!