Judging by the screen captures provided, 360 version seems suffer terrible dithering.

Since both version of GTA had the same rendering res, the same level of AA, IGN review comments like ‘more AA on PS3, or PS3 version smoother’ are probably related to dither in 360 verison.

If that’s the case, what could have caused this in 360 version?

Could it be the level of HDR? (like the limited RGB pallete of FP10 HDR commonly used in 360 games)

Actually, this is not the first time I have noticed such difference, the Burnout Paradise had 360 version to dither a bit especially for distant object like trees. – beyond3d