Being one who has never touched a Far Cry game, I wasn't sure what to expect going into Far Cry 2. I'm really, really enjoying it so far.
The draw of the game is obviously it's huge African environments. You can go around, shoot things, earn safehouses, find diamonds, steal vehicles, scout out areas for supplies, upgrade your weapons with said diamonds, and work for either of the two fighting sides.
I've heard people complain that driving from place to place can get annoying. Sure, it sounds annoying, right? Having to drive for like 5 minutes just to get to a mission and then failing the mission can get a little repetitive, but I think it adds to the experience more than anything. While traversing the wide-open environments, you get a sense of just how huge the game really is. There are bus stations that take you to each corner of the map, but you will have to find a vehicle or someone in a vehicle will find you. So far I haven't found myself in a position where transportation wasn't available.
When you do fuck up on a missions, one of your "buddies" in the game will usually come and save your ass. This is really pretty cool because once they drag you aside they'll cover you while you take a minute to heal and if they get seriously injured you can return the favor so they can help you later on.
It feels sort of like Grand Theft Auto with it's sandbox gameplay. You can really do anything you want, and I find that really addicting.