Immersive world spoilt by bad design choices.
Liked:
The World - Wonderfully rendered, the open landscape feels alive. You can almost feel the heat beating down on you as you trek through the land. The games sandbox nature keeps you moving around allowing you to see as much of it as possible.
The Buddy System - If you free captured expats then they will become your buddies, tell them you are on a mission and they will be ready to back you up when it all goes to hell. If you die then your best buddy will come along to rescue you (only once though) which can be helpfully when you get run over and instakilled by a car you didn't see.
Disliked:
The Respawning - There are checkpoints around the map where enemies hang out, they will attack on site, and it can be very annoying to clear out an outpost only for it to be repopulated as soon as you round a corner.
The AI - The AI is very determined, even if you pass them at high speed in a jeep, they will chase you until they catch up (especially if they too are in a vehicle) and won't rest until you are dead. They also can see through bushes, making concealment pointless (except for hiding the enemies from you).
The Weapons' Range - There is a large damage modifier for weapons over range (except for sniper rifles) and this makes sense. However, it is a little bit over the top; trying to kill someone at 200 meters with an AK ends up with you using 30 rounds to barely any effect. This is compounded by the open world nature of the game, across the plains there is little cover so taking out snipers can be a real pain if you don't have some kind of sniper rifle.
Both:
Mission and Story - While the missions themselves are fun, there is little variety (blow something up, shoot people). There is a choice to subvert each faction mission, but these have little effect (helps upgrade your safe houses), but has no consequences with the faction you were working for and just drags the missions out.
Summary:
A great, immersive, world spoilt by quickly respawning enemies, badly designed weapons and bland missions.