Resistance: Fall of Man > all other PS3 exclusives, IMO. Yeah, it is a few years old. Yeah the graphics aren't as great as current games. But if all you care about is graphics, you should be more interested in purchasing an imagination than anything else. For me, graphics are not an extremely important consideration when it comes into buying a game. It's gameplay, plot, design, and if it is actually fun.
So yeah, R:FoM is probably the most fun I've had with my PS3, barring Fallout 3. And do NOT, under any circumstances, get Resistance 2! It's shit. Complete shit, when compared to the original.