FPS games on game consoles are usually less fast paced than on the PC, this also due to different controls. Rock solid 30 FPS like in Resistance 1 is IMO fine, 720p is fine as well considering most people only have a HD Ready HDTV.
If at this point they could have done 1080p and/or 60 FPS without important sacrifices, they would have done so. Resistance 2 is very ambitious in other regards (said to include huge boss battles, online multiplayer support unlike no other FPS game befiore it, insane amount of onscreen activity, etc) and I am really looking forward to this game. 
I trust Insomniac to show off a good end result, technically far more impressive than shooters we have seen so far on the PS3.