As far as this game, it's short, and I would have thought it shorter had I not been writing this guide while playing, among other things that interrupted playing time. You get six hours, seven hours tops, but that should not be a knock against this game. Just like Call of Duty 4, this game cuts out the filler and delivers solid gameplay from start to finish. Just think of it this way: if you like condensed, more solid gameplay that is short, you'll not feel cheated at all, and if you prefer as much playing time as possible with as much repitition as can be tolerated, go grab Mass Effect or Assassin's Creed (yeah, those games are great, but not perfect).
This game is way smooth for visuals - something about maxing out the processor or something like that. It's got great graphics, sounds awesome, good enough story that even ties into the other two titles, and the combat is pure fun. If you got a PSP, no reason to pass this up.