The lack of squadmates was not a problem for me, as I tend to like to lone wolf it. As noted, though, now there are squaddies, which is cool when combined with the more immersive modes, so you can specialize and not feel obligated to do everything (and you can actually make the one main weapon limit option work).
Enemy AI is, well, Ubisoft enemy AI. The biggest Breakpoint specific issue for me is that the enemy simply will not stop talking. Even with all the over target icons turned off in full immersion mode, you just have to sit there for a moment and the enemies will let you know where they are by having loud and useless conversations without pause.