Overall I found the combat to be better, harder and more enjoyable. It required me to be on my guard more, dodge and run away from battles more often. I enjoy the variety of weapons, even if somehow Arno never figures out how to pick up a dropped weapon from an enemy. I don'y miss the super kick from 4 that instantly killed enemies. That made it too easy.
I do notice the enemy AI is far, far dumber. I rarely see them follow me everywhere, especially climbing up buildings. Mostly they just sit down on ground level and forget about me after the timer runs out.
But really, what bothers me most is the complete inability to grab people [or I have at least I never been able to figure it out]. It was a genuine tactic in previous games to grab someone and push/throw them off a ledge for an insta-death or push them into a wall to stumble them and get them out of combat for a cycle or two. Same for picking up a body and placing it so a patrolling enemy is distracted.
If I could make one combat change it would be to bring back the grab function. I miss throwing the roof guards off a tall building. It was just fun. :-)