The fact that it runs smooth makes it a lot more enjoyable to me than a game that looks 2x better but has frame rate problems.
For example Oblivion looks great at times. But the frame rate is completly unacceptable. When the "Huge battle" at the end of Oblivion consists of about 16 characters total and the frame rate drops lower than 10fps - this is a problem and a total wet blanket to the overall experience. I really don't care how it looks in still shots or how it looks in 1 on 1 combat if when the parts of the game that are supposed to be epic become a slide show.
Resistance runs silky smooth, even in split screen co-op. I never noticed any slow down even in huge battles where it felt like there were 50 some characters fighting in one area, friendly and foe, going at it.
The worse you can say about the graphics is that it's a bit mono chromatic. And for that reason the excelent graphics don't really pop out at you. But at least it's very consistant and detailed.
As far as FPS games go. For me I think I can easily say it's the best looking FPS I've played. And I've played just about every PC FPS game out there.