An awesome who cares how short it is single player campaign and a robust balanced MP make CoD4 a nice pakage.
For the PS3 this is exactly the meaty blockbuster shooter that my system needed. Warhawk has been a fun MP experience, but still doesn't fill the plate all the way for the FPS genre. CoD4 comes with a great cinematic single player campaign and a satisfying MP.
The main story follows a fictional story about a middle eastern uprising backed by a Russian terrorist organization. The story follows mostly in the eyes of two different characters: a British SAS named Soap and a US marine named Jackson. The story bounces back and forth on the two different fronts of this uprising in order to stop the threat of the use of nuclear devices. The whole story takes place in less than weeks time and feels pretty intense and non stop as it jumps from one battle to the next. Each level isn't a chaotic battlefield mayhem though. The story changes its pacing pretty well. Half the levels are urban warfare, and mixed in are a few sneaking missions, a few missions where you are ambushed and outnumbered 50 to 1, and even a mission that is a complete changeup from the FPS formula where you man the massive cannons of a gunship circling a thousand feet off the ground to help the troops below. Scripted sequences, that even though they funnel you or put you on rails, offer a wonderfull interactive cenematic experience. Some areas of the game may seem exessively difficult in scale to the rest of the game and could require a dozen restarts. Generally these parts need some ingenuity or gutsy luck and the payoff feels pretty good. There were no parts of the game I felt like giving up no matter how impossible it may have seemed. I agree with those who say to start on the regular difficulty. Enjoy the game's story like sitting back to watch a good war movie, The harder settings are rewarding but distract from the story by inevitable dying and restarting. The single player campaign does end up about 6 hours to beat, so Im sure you've heard, but its meaty and intense and wont leave you needing more because this meal has filled you up. Just in case you're still hungry the single player is just as good the second time around on the harder settings or you can try to best your score in the arcade modes.
For dessert the Multiplayer gives a tasty experience. It may not have the bells and whistles some MPs may have now, but it has all the important stuff and a neat class feature that lets you setup and balance your character to your liking. For the first time in a while I fully enjoyed a team based FPS. Most of this is to do with that everyone spawns in with the weapons they already want, so no one is running from the pack to get a powerup or find a weapon. The maps are done well enough that a four member squad can leapfrog through coverpoints, but sometimes doorways can get crowded. It is nice to know that at most times someone probably has your back, or that they appreciate that you're right next to them watching theirs.
Points are scored by different criteria in matches. These points level you up. On reaching certain levels game modes and weapons are unlocked. For example, only free for all and team deathmatch are first available. After reaching I think level 6 you unlock big team modes and point capture. This gives incentive for replay and also eases you gradually into the game. It also keeps out complete noobs in gametypes that they could completely ruin.
Niether singler or multiplayer alone would warrant a purchase of the game, but the pakage together is a worthy experience. If MP was never your thing maybe rent first to see if you like it and play the single player campaign. It should only take you a day or two to beat.