I don't have GoW2, but here's my --limited-- experience with PS3 upscaling (using firmware ver. 1.90, 1080i through an HDMI cable to an LCD HDTV).
Games: Soul Calibur 3 looked noticeably better. Much, much cleaner. Virtua Fighter Evo didn't fare as well. The character models looked jarring sharp and plasticky, while the backgrounds looked like ass. Looks like I'll be buying V after all. Burnout 3 looked better, but not as much as SC3.
Films: Watched the opening of SW:RotS and it looked fantastic. Then I tried something actually shot using real material like flesh, cloth and wood, ie Master and Commander, which looked nice, but not that much better.
So my hasty conclusion is that the upscaling works better on some sources than others, and when it works its very nice.
Unless of course, it works that same way every time and my eyes are simply knackered...