A jaw-dropping, mind-bending masterpiece.
The difference here is that Crysis doesn't attempt as much of the realism that COD4 did, so the "Wow"s are more because of the spectacle of the science fiction world that the game offers the player.
On the technical side, I have a AMD X2 4800+, 3GB of Corsair RAM and a 8800GT and I'm running the game at the highest graphical settings, save for 4X anti-aliasing instead of 8x and the frame-rate has been smooth for the majority of the gameplay.
Visually, the game is breath-taking. 'Near photo-realism' is the best way to describe it. I say this because there was a moment I was standing on top of a hill and the sun was coming up, 'morning-time' in the game, and the way the sunlight illuminated everything was exactly how it does in real-life, to stunning effect. You could almost FEEL how cold it must've been in the game world in that 'morning'.
The controls are solid, the weapons are powerful, even if many of the enemies are armored to the hilt and require a few headshots to take down. I experienced a few graphical hiccups and a gameplay bug or two along the way, but this takes nothing away from the fact that Crytek has crafted a technical and narrative achievement.
I've tried, but words don't do the game justice, only the experience itself can. It's a beautiful blend of action, science fiction, mystery and suspense that I don't want to end. Being able to play as an ass-kicking, nano-suit wearing super soldier doesn't hurt either.