Alright, so I bought the game and played around 3 to 4 hours today.
It´s actually pretty good. The open world is huuge, looks gorgeous and all sorts of different animals add life to it.
One of the main problems of FC2, enemies constantly reoccupying outposts, was solved as you conquer them permantently now. There are many different guns of which some you can costumize and different vehicles.
The crafting system is a bit "meh", though, but otherwise the game seems very promising. The story is pretty good as well and I´m quite excited to see what´ll happen later on.