Repetitive missions. You're in the savannah and even during daytime it's dark as hell in some areas, like under trees
But the biggest drawback in my opinion is the fact that you're in the friggin joungle and it's dark as hell in certain areas.. I mean the shadows in this game is pretty much pitch black. If you're inside a building, eventho the building has windows and an open door - it will be very dark and hard to see stuff, and if you look at out the door, it will be so bright you can't see anything.
The world looks pretty much the same, there's small camps with bandits that respawn every once in a while. The bandits are always the same, they are dumb and runs around like headless chickens when shots been fired. If you shoot someone, they will know exactly where you are, eventho they can't see you.. depending on whether you've got a silencer attacked to your weapon or not.
Another huge drawback is the weapons and their attachments. There's so few weapons in this game and it's just about 1 attachment for each pistol or SMG - a silencer. Sure you can slightly increase the gun accuracy and magazine capacity, but how fun is that compared to red dot sights, ACOG sights, Grenade launchers, etc. Play this game for 20 minutes and you've pretty much played the entire game, that's how repetitive it is.