Great combat simulator. Difficult, time consuming, interestingly addictive.
I like the game a lot and enjoy the realism, but even I get frustrated. If you are new to the series you definitely want to take it slow and do the training missions more than once, especially the shooting range. Quite a bit of the technical aspect of the game was the development of the ballistics.
The biggest drawback for most will be the graphics, since they aren't that great, and in order to turn the detailed graphic settings up you will need a fairly powerful computer. I have one of the newest gaming laptops that was just released and I still have to turn my settings down to the low and high marks, depending on what details I'm changing.
Overall, this is an excellent game if you are looking for more than the realism out of your shooters, but don't get frustrated and give up too quickly. Give yourself time to get over the learning curve and you'll be hunched over your keyboard digging the crust out of your eyes more than you'll like.