Couldn't ask for much more in a FPS.
The single player experience is short but I didn't have a problem with that.
For me most games get boring after a while and I lose the desire to finish them but not with this game.
The checkpoint system was excellent. You do a bit, you a reach check point, you die, you restart at the last check point. Sounds easy enough but so many games seem to screw it up. I never felt frustrated with any levels and the longest any area took to do was maybe twenty to thirty minutes and that was usually due to me not being smart enough to figure out what to do right away.
The controls were tight and while I'm not a big fan of run being assigned to R3, it wasn't that big a deal.
Haven't played online but the offline multi-player is fun.
The only real problem I had was that the game does not allow you to play against bots.
I didn't experience any slow downs. The only time I might have noticed something was maybe a second or two when a level was loading but that never affected gameplay.
For the record, I ran the game on a PS3 not connected to the internet and was able to finish the game without any glitches or patches. Nice to see a game that actually got tested before it was released.