I have to say I am extremely impressed with this game on almost every level. This is the first military shooter I have liked in a long time that wasn't made by Red Storm Entertainment. I am a huge fan of the Rainbow 6 (Tom Clancy) series of PC games with my favorite being the original Ghost Recon. Even though the graphics engine is very dated, the game is still a blast and I love non-linear gameplay where you are out in the open and can go wherever you want. Now this game is in fact very linear (at least in the single player campaigns), but since you are a soldier in a squad and not the leader, you just follow your group around and it still feels rather non-linear with all the paths in the game being sufficiently wide to perpetuate that illusion.
You actually sort of jump around as different characters in different battlefield roles and situations but the game has a certain continuity to it and the story line and scripting are extremely entertaining. The story is set somewhat in the future and is your typical Middle East/Russian vs. the free world conflict so you get to see LOTS of different types of landscapes.
Now the gameplay itself is a complete BLAST! It's like watching the movie Saving Private Ryan but you are IN the movie running around getting shot at and of course shooting back. Activision really did a good job of capturing what I imagine to be a realistic battlefield simulation (I've never been in one myself)... sheer chaos! Bullets whizzing over head and through the walls, explosions everywhere, and you get more than the mere insinuation of large scale warfare in that you can see tracers and explosions happening blocks away from where you are at any given time. Now those are the city battles... there are plenty of recon missions where you are sneaking through country fields or bogs and hiding in the grass from the bad guys, and in the opening section you are dropped aboard a huge cargo ship on raging ocean waves in the Bering Straight. You get to use multiple weapons and can pick up dropped weapons at any point. You can dodge, dip, duck, dive... and dodge. Well ok not exactly but you can crouch, lie down, crawl, sprint and jump over obstacles. There are even a few missions where you serve as gunner on aircraft.
Below I've recorded one of the coolest sections (in my opinion) of the entire game and you aren't even running around with a machine gun. Instead you get to cycle through one of the three gunners aboard an AC-130 that is circling a night time ground operation. You get to choose from the 25mm gatling gun, the 40mm L60 cannon or (my personal favorite) the 105mm M102 which would take out most of your back yard with one shot.
This one section is probably the most realistic military simulation I have EVER played... hopefully the smallness of the video won't diminish the effect, which on a 22" widescreen LCD is stunningly cool!!
Here is a larger version you can download (but don't send the link around... I don't want to have my bandwidth killed) - http://220.127.116.11/users/COD4-scene.wmv
Obviously I am giving this game a big thumbs up... if you are into the military shooter genre, don't miss this game!!