Combat is "realistic", which means the aiming is somewhat of a pain. Supposedly there will be an update to fix this eventually, not sure when though...
It takes a while to get used to, especially if you play Halo or COD4. The game itself was.... Alright, I guess. Characters were thoroughly unlikeable and said "fuck" every 5 seconds or so, and the last mission is basically nothing but a grind-fest. Along with that, all the guns that I liked were replaced with an overpowered, incredibly inaccurate machine gun, which requires you to fire in bursts of maybe 1 or 2 shots. Online isn't bad, again the controls are a pain, but it can be fun to play. On top of all that, it has bots, which are nice to practice against or just play with. The leveling up is also a bit annoying, since you don't seem to get any experience if you leave a game. And games CAN take as long as an hour to complete.
Overall, at it's best, the game is fun. At it's worst, it's an immature shooter with bad controls, boring story mode, incredibly annoying boss battles, and a severe potty mouth. 7/10
*EDIT* The graphics are quite pretty, though.