God or War (and God of War 2) may be the best looking PS2 game but the Gamecube and XBox produced launch games which surpassed everything the PS2 ever produce as far as technical measures go.
Most late generation improvements in the visual apearance of games comes from a full understanding of the limitations of the system, mainly from artists who are experienced in not wasting 'resources' create 'ideal' assets for the platform in question. As an example of what I am talking about, back in the day when Unreal Tournament was popular it had a massive mod community; if I remember correctly, an average (to bad) character model would be in the 800 to 1200 polygon range with a texture that was 256x256 , a good model looked (essentially) the same at took 400 to 600 polygons and had a texture that was 128x128.
Early in a generation most modelers and texture artists are working with dramatically higher levels of resources and tend to waste them from lack of understanding ... by their third project they have learned to waste far less resources creating assets which means that you can either have better looking assets or more assets on screen.
