Going in circles...
I'm not sure why developers are turning toward this trend, but repetitive gaming is NOT the way to go, and calling this a sandbox game does not mean that every mission has to be the same. Look at other sandbox-style games, like the two mentioned earlier, as well as GTA:SA and STALKER. These game were open, but still had a funnel like design that kept pushing you toward the bigger picture. Sadly, I still have no idea what the bigger picture is in Far Cry 2. The fact that the AI is dumb as mud (we've receded back to the days of Doom 2, where enemies just charge at you as if they are all coked-up football players with no peripheral vision) and the touted 'buddy system' makes absolutely no sense (mine can't seem to keep themselves alive long enough for me to get there...oh and I killed one, because they were aiming in my direction when I did get there) is making me wonder what the real virtues of this game are at all. I mean pretty graphic engines are a dime a dozen these days, and designing a good one doesn't mean that you can ignore all of the other aspects of the game. Buy Crysis:Warhead instead and really enjoy yourself.
Just my 2 cents...