So far, the only things I've noticed is the game now tells you when someone engages on a special enemy and it makes their icon on the minimap change. Also, the Hellfire ring, because my friend can be a jackass sometimes.
Other than that, we are only up to the spider cave now (third video SHOULD be the rest of act 1) and I haven't noticed anything new.
OH!!! I am still pissed that MY CHARACTER'S WINGS DON'T FUCKING STAY ON. WHAT THE HELL BLIZZARD?! Why is this so damn difficult? I want the wings on, keep em on. This has annoyed me since day one.