Pros: Improvement from the previous Call of Duty games, more realistic, varied difficulty levels.
Cons: limited amount of players allowed during multiplayer mode, currently experiencing trouble on Xbox live.
The bottom line: If you don't own it yet, go out and buy it today. It is the best shooter game out so far.
I was not a huge fan of all the previous Call of Duty games and never purchased any of them. But Call of Duty 4 is a must have. I am a huge Ghost Recon fan, but I have definitely dedicated my time to playing Call of Duty 4. The graphics are amazing, as expected to be. The weapon selection is plentiful. The only drawback I see while playing on Xbox Live is that the better weapons do not get unlocked until you rank up. Although that idea seems grand, it puts newer players at a huge disadvantage when they initially start playing. The "veteran" players have modified their weapons with scopes and silencers, increased their abilities with the 3 perk options, and have access to all the weapons. So as you run out there with your M-16 and MP5, be prepared to get beat down the first day or two. But a gamer is a gamer. My kill to death ratio was still over .500 in less than 3 hours of playing the game. This game will suck the life out of you. You will probably lose contact from real human being as you are glued to your tv playing this game non-stop. I usually only play on Xbox Live, but I was still impressed with the campaign mode. Since it is technically modern warfare, this game reminds me of Ghost Recon. Maybe that is why I love this game so much. Either way I see it, if you love realistic shooter games, you would be crazy to not get this one.