Am over 2/3 the way through the game and though I would provide some high level inputs.
1) I now see them (enemies) using their feats to good effect.
2) They (enemies) also with now redirect to people who inflict damage on them. This one makes a sniping mage a bit more challenging since if you are too close they ill turn on you and chew you up.
3) Enemies will redirect to a mage who is casting spells (even spells that do not damage them) if the mage gets too close.
4) An odd thing I see now is what I call "homing enemies". These are enemies who will follow you around the world to the exclusion of all else. If you use your stone of recall for example, they know exactly where you are and will eventually catch up with you. Shadow Fiends are the worse as once they target on the PC, they never switch targets no matter how much damage your henchmen inflict on them.
On the whole, I like the AI updates, though something should be done about "homing enemies". They need to break focus when you are gone.
Ugh! Just when you think they can't make it worse, they do. It is now SO SENSITIVE that I get caught in way more places then I used to. Heck the first place you see it is in the prelude. The guy to talk to to open the door to Aribeth acts as a blocker and you can't move through the door by clicking it. You first need to move to the side of him and then click the door.
I could go one about this with many more examples, but will leave it at this.
Be sure to turn off the cloud saves unless you really want them. I went so many months with my saves getting corrupted by that cloud save mechanic before Sarevok57 saved me with his help!
Overall I find the game much more challenging (I play on D&D Hardcore rules) then in the past and I like what has been done. Keep up the good work!