Favorite in the series, and I payed 1, 2, 3, and some of 4. ((and I keep forgetting primal exists). HUGE freedom in pacing, choice of missions, and SO MANY "treasure-hunts" where you can take a break from guns with some interesting/memorable little jaunts.
Maybe I'm just playing post-patch, but the different ammo types aren't as absurd as some forum posts whine about, since armor piercing doesn't do significantly reduced damage to non-armored enemies, while hollow-points drop them like they should. Really it's all about your character level, which if you take your time like I do with Far Cry games and attack more of the content instead of trying to rush through the story, you'll outlevel and out-gun enemies enough that ammo type only empowers you without hindering you. Also, I F%%KING LOVE poison! Turning a base of enemies on each other with a few sniper shots adds fun variety.
Don't understand the hate, except I understand annoyance at over-used voicelines and cringe here and there from the writing.
Also I should add that I don't usually get *immersed* in gameworlds to the point of getting distracted from shanking fools and shouting enemies off cliffs.... but this game, HOT DAMN everything from the textures of every piece of nature to the way they've animated bird flocks or clouds appearing and dissapearing... it can really draw you in when the lighting is right, and you got the ambient sounds turned up. 9/10 easily for me because of the freedom of destruction, and all these other special touched.
Oh, and weapon camos for days.