Uhm.. as someone who LOVED JC2, the driving was subpar and the shooting was pretty barebones.
What was amazing about it was the huge map an the grappling hook interactions and possibilities, along with the extreme simplicity of the missions that, however allowed a more free form approach than if they were scripted and complicated.
GTAV seem to have far more complex and solid driving and shooting, but i dont think you can expect the same level of crazyness, although judging from trailer 2, theres a lot of crazy shit, still.
Also lets not forget that it will take fauna and random encounters from RDR, those should shake things up quite a bit.