Well, one word to sum up, outstanding.
The game puts you in the spotlight, you given a start of a discussion between two high ranking men, who do not look ordinary and from there, you probably have no idea what is going on.
This is what puzzled me at first but once the game starts, you are in the hotseat, you train and learn what the ins and outs are of your capabilities. Once training is complete, you learn on instinct, your decisions determine how the relationship builds up between your friends and foes, whilst uncovering a mass consipiracy.
There are no cutscenes, the action is non-stop, from taking out terrorists to achieve your objectives to buying ammo or other equipment from soldiers to accomplishing the main goal, how you want the world to turn out to be. You at times either feel anger and disgust after being stabbed in the back and you have to find alternative ways round to complete your objective, there are several ways of doing it.
The music is enthrawling, it attaches you to the game and keeps you on your toes because you never know what could be around the corner. The game allows you to explore the environment and plan on how to complete objectives by stealth or all out offensive, by stealth, you could use darts to take out enemies and hide the bodies or openly by using assault rifles and grenades. Its no simply FPS, its a combination of action and simulation, you need to establish yourself by examining what you can do and use against your enemies and take the course of action and use whatever means necessary to complete your goals.
This game can be addictive, even bringing yourself back to it even after completing it and finding other ways to complete it. Its a good read and understanding as well fun on the sides. It doesn't matter how old the game is, I would still go back reload it and play it many times over and over again.