one of the best in the series. The huge array of weapons and gadgets will have you mixin' it up for quite awhile.
You'll keep playing this game just for the A.I. difficulties. Yes, after awhile you'll get bored; and when that happens you can just take it online. This is the part you will love.
If you want cramped spaces, choose the office. If you like large open spaces choose romania. (my favorite) If you are particulary good at sniping you are probably gonna be hearing, "Holy Crap! look out people theres like 3 people in the area" This is a really rewarding message, because then you can brag and say, "nope just me." and they will drop jaws in awe. The advantage of being good at one weapon, or strategy comes in when you join a clan and get recruited for a specific job. There is offensive, this job usually means ur carrying shotguns, rockets, and grenades. There is defensive, this means you guard your base (or flag if your playing ctf) with mines, and machine guns. There is the classic sniper, the name says it all. You sit back with a drink and pick off anyone who comes into your vision. There is also the stealth guy, his job is only necessary when playing ctf. He uses stealth, speed, and gadgets to get to the flag and deliver it safely to your base.
If you want it all, i suggest playing Capture the Flag. It'll keep you occupied for hours and hours.