Simply one of the best developed fps in gaming history...period.
CoD4 is one of the best developed games in the history of gaming. Imagine when you first loaded Half-Life 1, and you felt like "hey, I'm actually this person, looking around as if I am there before all the crap happens." Well take that feeling and multiply it 100 fold. You have CoD4... to put it simply... it is an experience.
It feels like what a fps should be, a cinematic movie in which you control the actor. The actors play out their roles perfectly, and you play yours. You are not alone, but rather one person in a team and your actions work along with theirs. This game, could be used for military training, or if recorded, played back as a movie.
There are no cons to this game. It runs perfectly, everything is perfect. Oh people might complain that its too short, but thats necessarily a con. You see, this game was also made for consoles, and studies have shown console fps players prefer shorter games. It must have taken them a long time to make a game with kind of polish and quality.
I would rather play a polished and well developed game thats short, than a non polished average game that is longer. This is what Quality is folks, and these kinds of games are not cheap to make.
After you finish the game ( suggest not playing it on easy ), you are given the option to replay levels based on a point system. This allows for some replay value so you can brag about how fast and accurate you ran the level.
Thats not all though, its a multi-player game, and one hell of one as well. Play online after the single player campaign is over, it doesn't get old, its just amazing.
Because of CoD4, the standards of gaming have just been reset, and most games will be hard pressed to meet this level of fun, development and polish.
Good show. Keep it up CoD4 team.