Far Cry 2 was a game that got good reviews from the press, but has inevitably gotten a reputation from most gamers as a boring, and repetitive game bogged down by respawning enemy checkpoints and constant hostile patrols. The first time I played the game, I had many of the same concerns. The way the game generally played out for me was that I would drive straight for my mission objective, along the way stopping several times to switch to my turret and take out a patrol, or stopping to clear out a checkpoint, and then I would get to do much the same thing at the mission site. And this was compounded by the fact that I usually had to repair me vehicle or switch to a new one in each of these encounters and that the checkpoints respawn when you leave that cell in the map. My first play through was about 4 hours and I quit.
Unfortunately, I don't think many people got beyond this experience. Far Cry 2 is, as much as I hate the phrase, the kind of game that I think you have to "play right" to enjoy. The checkpoints respawn, but that only encourages you to rough it offroad, find ways around them, and figure out the most efficient ways to clear them out. The patrols are always hostile and will chase you down for long distances, but they have consistent patrol routes that you can take advantage of to avoid or ambush them. Far Cry 2 is a game that encourages controlling every encounter to give yourself the advantage. Every mission is simply a single objective with no indication of how you have to approach it and each location is open-ended and smartly designed.
People also complained about the psuedo-realistic elements of the game that put you, unlike most FPS's, in a constant position of disadvantage. Weapons jam (especially those picked up by enemies), your car will break down if fired on and need to be repaired, you have malaria attacks regular interviews that essentially incapacitate you until you take your pill, fire can be useful, but it can become a serious hazard if the wind changes and blows it your way.
All of these elements add to the juxtaposition of unpredictability and control that the game thrives on. It encourages you to carefully plan your every move with the constant knowledge that your efforts could be undermined by all of these elements that don't always go in your favor. What could have been an easy search and destroy can turn into a down and out firefight when your carefully timed rocket turns out to be a dud. A planned sniper position could become useless as you have to switch to your secondary weapon because your sniper rifle breaks.
There is no other game quite like this one, and unfortunately there may never be, but you;ll never experience it if you don't give it a chance to shine.