Played this a LOT back in the day, the game itself is fine, has a steep learning curve and there are many agents with different abilities to choose from.

By far the best game of the series, which not only has pretty satisfying gameplay, but also the best characters in all of the Far Cry games.
The protagonist actualy feels like a person with feelings, needs and thoughts, not some mindless robot like some other protagonists in the series. He starts out as a wimpy ass kid and he's completely terrified when he kills his first human. But he has to adapt to the tough and deadly world around him. He slowly becomes a serial killer with no mercy, and he actually starts to enjoy killing. He also works perfectly with the other side characters, but mainly with the antagonist, Vaas.
On the topic of that, let's talk about the bad guys. You've got Vaas and Boyt, two completely different characters; Vaas is truly one of the best villains in the entire gaming insustry. He is a real psychopath and you as the player are actually afraid of him. A lot of his lines are iconic and that's aldo because his great voice actor Michael Mando. Also, as I already said, the main protagonist's relationship with Vaas is really interesting, almost as if they need each other. That and many other things is why his death is actually really emotional and really hits you.
On the other hand, Boyt doesn't have much screentime, so that's why I cannot really create an opinion on him. He's just trying so hard to be evil, but Vaas is miles better than him at that. That's why I think it's a shame that he's supposed to be the main villain and not Vaas.
The gameplay itself is pretty good, the guns are simple and effective. The only thing I'm not really a fan of are the "collectible weapons", they are the strongest and most fun weapons in the game, but you slowly unlock them by colleting a certain amount of some collectibles. But as a whole the gameplay is really fun.
So overall I think this is a great game and definitely the best one in the entire Far Cry series, and I think it's a must - play for every FPS fan.