I don't know why I'm bothering saying this, but this game does look and run significantly better on the PS3.
Smoother framerate on the PS3 version. 360 version may have more "high points", but it's low points are far more noticeable than they are on the PS3. The PS3 version seems to be locked around 30, while the 360 seems to bounce from 40 to 20 on a regular basis.
Bullshit. I own the game on both systems and went back and forth between the two and the framerate on the PS3 was noticeably worse. Try driving over one of the bridges at full speed with heavy traffic on the PS3 and then do the same on the 360. The PS3 drops to N64 Perfect Dark levels of framerate. Locked at 30? Pfft. Only if you're fucking high.
The texture pop-in is worse on the 360 and the shimmering shadows are more pronounced as well but the game does run at a higher resolution and honestly it was a refreshing change to go back to the 360 GTA4 after playing the PS3 version for its visual clarity. The jaggy vasoline filter thing on the PS3 is just too much after awhile.
I guess we'll just have to agree to disagree on that. Don't know what more to tell you. I bought the PS3 version, and wasn't that excited about the game, but the framerate never cought my attention. My friend brings over his 360 version a couple weeks ago, and I was shocked at how much I was noticing the framerate, and the shadows, and the texture pop in. I didn't play for more than 15 minutes, but those three things stuck out like a sore thumb to me, while they never did so in the 5 hours I spent on the PS3 version.
Also, your "vaseline" comments are silly. No, it's not as sharp as the 360 version, but only a fanboy would want to take it as far as using that word to describe it.
I have to say, it was really funny seeing that gaf thread about the graphics comparison of this game. When the reviews hit they were nearly unanimous that the PS3 version looked and ran the best. Well, 2 weeks later I check into that thread to find the gaf Xbots had beaten that thread to a pulp, and declared the "winnar" the 360 version. I guess 2 weeks time improved things for the 360 version.

I guess all those reviewers were wrong, and so was I when I saw them both on my own tv.