GTA4's major flaw is that despite an incredibly matured narrative and style, the excessively ribald humor is still there, the strip clubs are still there, the ragdoll physics are way over the top, etc. It just has too many moments of immaturity for it to be really perfect. That said it's fantastic, no doubt. I was just thinking the same thing, but more about the core gameplay mechanics than the humorous accoutrements. Walking out in the middle of the street and jacking whatever car whenever you need to get somewhere just doesn't seem like something the protagonist would do. GTA has, for better or worse, retained virtually every gameplay element from the days when it was a goofy arcade game with no story where the object was simply to rack up as many crimes as possible. Just because the option is there doesn't mean you have to indulge in it.