While executing people you are not invincible and you can be interrupted. That means after stabbing someone through the brain twice, while winding up for the third stab you can get shot in the head. Then someone can go over to the guy who got stabbed twice through the brain and pull him off the ground, ready to fight again.
The way horses move is what really puts me off. In M&B fighting on horseback was kinda like dogfighting because you had to take momentum and obstacles into account, but in this it seems so.... jittery and unnatural I guess?
Not that M&B horse mechanics were perfect either, but they were pretty good compared to this.
My biggest criticism perhaps is that people seem to move rather slowly. Maybe it's just because in M&B I like wearing lighter armor in multiplayer so I can move quicker =p
EDIT: Also, despite people saying they've played M&B and post a video of them playing this, I don't get the impression they've ever actually played M&B. Either they haven't played it for very long, or I'm not getting a feel for just how clunky (or not) WOtR is in comparison. I'd kinda like to try for myself just to see but...
EDIT 2: ...or you can't change which direction you attack or block like you can in M&B.