I'm only like an hour into it but so far it's 'meh' to me. The shooting is fairly loose, ai is typical rubish. It's pretty but most the missions I've done are the type I really don't get into. Things like 'drive this vehicle with shitty vehicle mechanics to point B in x time' or 'kill x enemies in the time limit'.
Again I've only just started but I'm not entirely impressed so far. But then again I though FC2 was fairly weak in the beginning but really got into the wide variety of weapons and the open world that lets you approach each 'quest' your way. Yea it had its issues, like insta-respawn check points. But hey at least in FC3 you can take the little side-areas over to stop respawns!