That, and enemies absorbed way too much damage. The animation was also goofy at hell at times, which combined with the goofy behavior and incredible damage tolerance to make for some kind of heavily armed distinguished mentally-challenged fellow army. Fix that, mix missions up (and remove the kamikaze jeeps), and the game will be nearly fixed right there.
I don't think keeping it in Africa would be bad, but more of Africa in a single environment would be nice. Even with jungle, marshland and savanna, the environments felt pretty uninteresting after a while. Snowy mountain ridges, deep wet jungle, that sort of stuff would have been nice. Keep the world open, but make the destinations more interesting, and varied.