GTA IV stands as the testament to how significant the improved hardware of the 7th gen was. A world much bigger than previous games, a fully implemented physics engine, procedural reactive animations, a metric fuck ton of radio channels and licensed music, TV shows within the game and seamless transitions between open world activities and open world traversal, just to name a few things that weren't related to the graphics. There's a reason why GTA IV got such rave reviews at launch, because it was the game that showed just what the hardware of the 7th gen was capable of doing. GTA IV has also aged terribly and is today a mediocre game at best, with a lot of people questioning how it could ever get such unanimous praise, which shows how commonplace the revolutionary features of GTA IV have become. People tend to forget how constrained games of the PS2/Xbox era actually were in terms of design space, because the paltry memory and processing power at the tail end of the 6th gen put a pretty low roof on how complex games could be.