Game starts off slow in a way, then speeds up - fast.
You can just about do anything you would expect, and the storyline is more than 50 hours for sure if you replay it (which after a break from the first play-through, you will) and take in all the missions you want (including side missions).
You start off with a short "tutorial" than you're dumped into a huge African enviroment faced with unlimited choices. You must encounter and maintain fighting forces, malaria and finding the Jackal.
It seems a little overwhelming at first, with few guns that occasionally jam and the fact that you don't quite have the skill-to-hunt-insanely-well-and-still-survive thing. You can play any way you'd like, be it throwing explosives, sneak in stealth, or just run-and-gun. It's not like tactics don't play a role here, of course. Running-and-gunning through a heavily guarded base with vehicles and snipers is not a good idea all the time, but feel free to try it if you're feeling ambitous. Thinking about the battle and scanning it out first could - and probably will - give you an upper hand. But enough tips.
The graphics are fabulous, and the day-night cycle is cool. Enemies do vary down to the clothing and faces, so its not repetitive. The missions however, are. Though if you vary the time of day, and the places you go, they don't seem repetitive at all.
If there's any flaws in this game, it's the travel time. Bus stops that automatically travel you to another stop do little to reduce this time, and enemies along the way are another annoying stop, and if they kill you it couldn't be more irritating. Thank God for tha quick-save feature.
Overall, however, it's a great game with good re-playability and tons of options. The flaws can be overlooked - its that good.