So I’m really right at the beginning of the game, but here’s my experience of the current AI.
At the first side mission to get the sniper rifle in the house, we have three Runners patrolling. I manage to get into the main building and a Runner comes up behind me and stays at the bottom of the stairs. He tries to shoot me sporadically but can’t seem to reach me, I think he can’t tilt his gun up to my position…? So I stand there and take him out easily. The front door is open but the other two are looking at each other around the left of the house ignoring our shooting match. I look out the window and take one out. The other stands there awaiting his fate - but not for long as I kill him.
At the farm a little further down the starting Island, I manage to get into a fight with a Hunter. I get into a barn and close the doors. I can hear him outside and he’s shooting through the walls (fairly accurately in my direction - though he is blind and I am trying to be as quiet as possible). I don’t mind shooting through the wooden walls, but the blind accuracy is a bit much (unless I am yet to discover they have motion sensing or something later on). I hear him move outside one of the doors and for some stupid reason I open the door onto him. This seems to push him back and now he’s just standing there, he doesn’t try to come in and I can now hear a Runner next to him - again not coming in. I can see the Hunter through the large gap in the hinge so I shoot him through it without any retaliation and he’s down. I do the same with the Runner who hasn’t responded to his mate’s death.
Short story - the AI needs work. Seemingly pathfinding is confused by exterior to interior travel. Reactions to events such as your big brother just been downed - time to take cover or rage attack. Right now it feels very work in progress.