This game is a very unique game, for many different reasons.
1) Graphics: Graphics do not define the overall quality of a game. Graphics are a bonus. However, this game has a pretty unique graphic style, which I admire, since it's different than what you'd find in a lot of games. The environmental graphics compliment the style rather nicely. The vehicle graphics also suited the style, as well as the way the water was implemented and used. Not the best graphics in the world, but I'd give this area a 9/10 for creativity, uniqueness, and consistency.
2) Animation: While the animations aren't flawless, they aren't in any way bad. The animations are fairly smooth, and many of them flow together rather nicely. The animations for vaulting are what I consider the weak link here. There are occasions where the model of the infantry grab the inside of the wall they're vaulting over, near the top. Whether it's an oversight or a graphical error, I'm not sure, but just thought I'd point it out. Overall, a solid 7/10, as there is plenty of room for improvement in this area. Like I said, it doesn't mean the animations are bad, but they could be better.
3) Combat: The combat is very realistic, as it doesn't take much to kill or be killed. A few bullets is all it takes to kill someone. Aiming accurately is, however, quite challenging, since you have to know what you are doing to get a good shot. Recoil has a huge impact on aiming, just as it would in reality. The longer you fire, the bigger the recoil. Reloading is all done manually, since there is no automatic reloading like most games. This forces you to check your magazine constantly to see if you have enough ammo loaded or if you need to reload. There are vests to absorb the impact from bullets, only the amount that they protect you from depends on the quality of the vest. I'd give this a solid 9/10 for realism, and the uniqueness of the reloading system.
To summarize it up, this game is creative and unique, creating a sandbox feel all the way through. The use of the combat system makes every shot count, as well as deadly. The graphics aren't the best in the world, but they work with the style, and are well made. Multiplayer is a very fun experience (from what I hear), and is recommended for anyone who enjoyed playing the main game. I give this game an overall rating of 8.4/10, due to graphical style, creativity, combat realism, and uniqueness.