I would to comment what I have hear and seen during the gameplay.
In single player I have noticed that sometimes the voices of the characters are outsync or I hear two dialogs at same time, some ocations there is a delay on the dailogs or there is no dialogs.
Other thing a have noticed is when the enemy or ally are just standing they are not carry their weapon but they think the have a weapons on their hands.
As a other users report, enemies don't react in the way I espect but in my case i saw when they are walking until they run into wall trying to get through.
Does anyone have seen this kind of glitch?