CoD 4 is an awesome game, with great campaign and superb multiplayer. Buy it!
Story: The story is great, and daringly realistic, featuring a shoot and ask questions later squad of marines, and a undercover sneaky squad of SAS. They both play differently. I prefered the SAS squad.
Graphics: The graphics are some of the best i've seen, and the weapon designs look amazing. The enemies look like they are real when they die, flailing around, or flying 10 feet when you shoot them with a Grenade. Explosions look cool, and the building details are almost life-like. The only thing I have to complain about is the american Sergeants' skin. He is black, and his skin looks like icing or putty. Weird.
Sound: Call of Duty 4 sounds like a real battlefield when you turn it up. Everything sounds like it should, and the weapons sound the bst of all. Nothing to complain about here.
Call of Duty 4 is a must buy for shooting fans, as it is intense and all together very fun.