Having played several hours of Resistance now, I can safely say that at times, it's more impressive than anything in GoW (GoW may be more impressive if all you count is normal maps -- although on average I think GoW may look a little better) -- there's tons more shit going on at any given point and it never loses a frame.
GoW looks great on average, but it sort of looks plain and boring in terms of the amount of stuff going on -- things floating in the air, number of enemies/friends, smoke, etc. Not a huge issue, but I think Resistance is being a little bit underrated just because it doesn't have a normal map on everything -- which is a pity, because it's pretty snazzy to see in motion if you pay attention to all the small details (for example: the snow in Resistance is perfectly done -- that's how weather effects should be! not the flat texture grid rain in GoW!)
I sort of have to agree with nAo... from a technology stand point Resistance is rather amazing. GoW does look very good and I'd say it is definitely one of the most impressive games to date, but Resistance is also quite impressive and I can't understand how anyone would give it much less than GoW in graphics department (I'd say they deserve the same score -- for different reasons). After playing GoW (and surprisingly enjoying the hell out of it), I don't think Resistance is lacking in any way in the graphics department.
side note: I agree with previous mentions that the PS3 controller is tons better for FPS games than PS2 controller was.