You know, what most people fail to realize is that many games, secretly, run at less-than-normal HD resolutions. Anyone remember that little game COD4? Apparently it, too, ran at 630p on both systems.
No one seems to complain about THAT game looking worse, on either system. In fact, I've never heard a single complaint about that game's graphics. Why complain about GTA IV's? In fact, I'll go one further and say, why complain about ANYTHING so minuscule?