A really good tip for the last room on the last level is to stay in the tunnel as long as you can. Pick off guys from the tunnel, stay on the right side while shooting guys on the left and vice versa.

Once you think you have taken out all the guys inch out of the tunnel to spawn more. Once the guy with the RPG fires at you you're almost done.

Hope this helps.

Yes, it is a kick a** game, I have a PS3 now and still pop it in to vent a little frustration.