To sum up previous ai from what I've experienced (played for about 5 months) 1. Ai for most of the alpha were completely brain dead, you could get near them without them even noticing you and they would never hit their target 2. Ai at then end of alpha and the start of beta were terminators, they could about face and shoot in a quarter of a second from ridiculously long ranges 3. Ai for most of beta have been pretty well balanced, using new skills like seeking cover and roaming more, however they had become more of an annoyance than a challenge, as they mostly didn't pose a threat to your safety 4. Ai since the quest update have regained some terminator like attributes like somewhat unrealistic precision (hitting a specific limb rather than center mass) as well as the ability to see through foliage.

Imo scav are currently the best they've ever been, my only issues with them is their ability to shoot a specific limb at long ranges as well as their ability to see through foliage, however I don't think the Ai are really any more powerful than a skilled player, it's just that they have a few dirty trick ls up their sleeve...

P.s. Sorry if the formatting is bad, since I am using the mobile site on my phone.