I was in a Nordic ruin and a forsworn activated a trap, ran over and pulled a lever. The trap was a hallway with swinging axes. Then she stood at the far end of the hallway to shoot arrows at me. I was rather impressed with that strategy, I haven't seen anything like that in Skyrim before.

I know the ruin of which you speak, and no, it's not a new feature.

That particular AI isn't new. She detected the danger and had to use a ranged weapon.

However, some of the new npcs like Serana have upgraded idle AI.