With it's incredible multiplayer and fantastic campaign, Call of Duty 4 is an incredible experience.
Story. There isn't a whole lot of story here. There are some terrorists. They are bad. Kill them. At least it doesn't try to be some massive action movie and fails (looks at MW2)
Presentation. The game has okay graphics. The textures look decent from far away, but up close they look incredibly pixelated and blurry. Same goes for shadows. Looks great from a distance, shoddy edges from up close. Character models are great. I especially love Captain Macmillan in a ghilly suit. They are very detailed and.... yeah.
Campaign. The campaign is great because it actually feels like what modern warfare would feel like, not something fantastical and action-movie-ish (looks at MW2 again). You go through mostly similar levels, except for a stealth mission and the final, mostly on-rails mission.
Multiplayer. This is where this game really shines. The game has a leveling-up system where you earn points for kills, assists, capturing objectives and match bonuses (probably more that I've forgotten too). As you level up you unlock more weapons, attachments and camo for your guns. You can only carry a large gun (such as an assault rifle, sub-machine gun, shotgun or sniper rifle) and a pistol. This makes it fair because if one sniper finds another and they have a close range battle, one can't just pull out his shotty and blow the other one away. Unless he has overkill (the most unbalanced perk in the game, letting you have two primary weapons). Perks are little powerups that give your character traits such as more damage, or more health. It's good that these are little, and don't usually change the course of the game too much (glares at MW2 with burning hatred).
Pros
Character Models
Fun campaign
Relatively balanced
Brilliant multiplayer
Cons
Graphics
Overkill