I would expect GOW3 to be damn near movie like with the graphics. Comparing GOW and GOW2 on the PS2 with other PS2 titles, visually they blew everything else away. I've already seen some beautiful artwork from the PS3 line up.
As fucking awesome as it was, I wish they had added the multiplayer content and other extras they were going to put in for Chains of Olympus on PSP. You can get a lot of replayability of it if you start from Normal and work your way up to God Mode though.
In fact, I wouldn't mind another PSP game, because unfortunately I only have a PS2. I still haven't played God of War II, but I LOVED God of War I and Chains. That's why I'm almost regretting I got a 360 just because of God of War III.