GTA 4 is huge. It's interaction space is limited however. The emphasis was put on your feeling that the world is big and you can live like gangster. The main vision for the game is gangster simulation. And huge amount of work was put into cinematic characters and story variety.
The game has a great and funny feel to it. It's obvious though that different parts of the game were designed by different people with different goals. You should make up your mind if you want to make immersive game or fun arcade game. I think that it's the job of creative director. Some things should not be in the game. Instead of doing stuff like arcade machines, games within the game you should develop gameplay more related to the core experience of the game. Variety in this game is huge. But content does not mean quality of design.
The game has a great and funny feel to it. It's obvious though that different parts of the game were designed by different people with different goals. You should make up your mind if you want to make immersive game or fun arcade game. I think that it's the job of creative director. Some things should not be in the game. Instead of doing stuff like arcade machines, games within the game you should develop gameplay more related to the core experience of the game. Variety in this game is huge. But content does not mean quality of design.