http://www.gamesradar.com/xbox360/grand-theft-auto-iv/news/gta-iv-360-vs-ps3/a-2008042812150303074/g-2006051014323586065
''We’ve played both console versions of GTA IV, and took the following video from the opening scene. We captured the raw video in uncompressed 720p, with no post-processing to either stream. Shown side-by-side, it’s quite difficult to tell the difference between the two versions. Only a highly trained eye can see the subtle shifts in color, the minor variations in shadow detail. Our conclusion: buy the one for the console you own. If you’re lucky enough to have both in your living room, your decision will have to be based on whether or not you want to pay Microsoft for Extra Content. The barely perceptible difference will have zero impact on your enjoyment of the game.''
There you have it. Looked kind of dark to me but the best Ive found so far.