I thought Far Cry 2 was an awful game but I'll try it again I guess.
I played it for about 3-4 hours the first time I tried it and though it was the most boring, broken FPS I've ever played. I thought the shooting was horrible, enemies took too many bullets, they could spot you through 3 fucking trees and tons of bushes, etc.
I put it down and gave it another shot 5-6 months later after listening to a bunch Idle Thumbs again, and went into it with a mindset of, I'm just going to take it slow, try to enjoy the game, and try to explore the systems in the game as best I can.
I thought it was pretty awesome after that. I also happened to pick the character that started with a flamethrower, which is so fun to use, and then realized you get a sniper rifle very early, which helps so much more than you could ever realize, since it basically gives you a telescope to scout ahead that is much faster and usable than the monocular that you can use with the map, which sucks.
Just try to play it like it's not just another FPS. Use the flamethrower or a molatov to start a fire in the brush near an enemy checkpoint, then either run away and snipe them all as they are fleeing, or just use the chaos to sneak past. On the missions where you need to kill someone in a convoy or a jeep, use your head and do stuff like set up a trap, rather than just chase after them in a jeep, then gun then down with the turret. Observe their path for a bit, then find a point in their route that is narrow, then block the path by parking a car in their way, then ambush the shit out of them by throwing grenades and starting fires.
It's the kind of game where you get more out of it when you put more into it. If you just drive places, then get in huge firefights, it's not a good game at all.