I once bought Crysis and Crysis Warhead very cheaply at Steam. And I can tell you safely that Crysis Warhead is a really good shooter. It has a much better story than the prequel, the hero or better the antihero is much more believable, cutscenes are so great, I was close to tears when he left a friend and got in rage. It was simply very well presented. I could feel what he felt.
Gameplay was faster and everything more dense then in Crysis.

Besides that the original Unreal was much better than many of the new shooters. I still play it again and again.

And there was a Starwars game, called Republic Commando, where you played some Clone warrior. It was so great, your AI comrades did so much, healing, sniping, using turrets, opening doors ect.

And there is L4D2, what a great game. AI in single player is so believable on both sides. Survivors help each other and react very good using tactics and stretegies. And the special enemies are so smart as well, using hideouts, tactics, working together in teams (one grabs you while another one spits acid when you cant move).

Really, there are better and smarter FPS than a scripted rail shooter.