Used to be Vice City, now it's IV and it's dlc.
I love it, I think the storyline was really good, more emotional, had kinda of a rpg feel with the choices you could make and generally I just thought the missions were really well done and quite different from each other, adding more variety which wasn't seen all that much in previous GTAs.
Graphically, it was much better but that's understandable since it's next gen and all that, the physics were great too.
Big improvement in gameplay, cover, blind fire and other additions were great.
In the end, I din't really enjoy IV like a sandbox game, thought it kinda failed in that aspect but as an action game, I think it really delivered a great experience.