Well, that’s a bit harsh. I bought Call of Duty 4 expressly for the purpose of playing online multi-player matches with friends, so the single player mode taking roughly 5 hours to play through doesn’t really count against the game. And, I did have it on “Recruit” difficulty… which, embarrassingly enough, is the difficulty setting the game itself recommended after I played through the training level.
So saying that it’s an awfully short single-player game is unfair, because it really didn’t need to be longer. It had a pretty decent story, as shooters go, with some genuinely tense moments, and absolutely gorgeous visuals.
Still, if you’re not looking for a multi-player game, it’s a rental.