It's a pretty good game, only thing I don't like about it is, when you die online you go into spectator mode until the round is over, but other than that it's a pretty good game, also no vehicles. Another thing to play all of the maps you have to go through different trainging courses, special forces is the hardest in my opinion, and believe me when I tell you, PAY ATTENTION TO THE MEDIC LECTURES, you have to listen to a few 10 or 20 minute lectures on medic training and then take a test and pass, if you don't pass you must go through the lecture again and take the test again. And you do know it's a free game, you can download the full game from their website, it's not a demo and there are no limitations. Let me know if you have any more questions on this, I haven't played it in a while but I can answer most things.
Here:
http://www.americasarmy.com/downloads/