Firstly, love your avatar
and secondly, they're not updating anything except a few game modes, weapons and missions. The graphics have had no touch ups since the last one - they look actually considerably worse. It's like they made the models and then just added shine and a plastic texture to them (again).
At least with GTA, they introduced a new Graphics and Physics engine to enhance the gameplay. I get it out of pure curiosity and to try out this Co Op Story Mode. Apart from that, couldn't really give a toss.