Two things I've noticed so far in my copy:
- Sometimes in battle, if I'm not actively controlling Nathaniel, he idly stands his "attack pose" and just gets wailed on by enemies
- Not as often as Nathaniel, but in battles Oghren will stand in place and wave his axe at nothing and be stuck in that animation until all enemies are dead.
 
Has this/something similar happened to anyone else?

I'm playing it on 360 and have had some totally crazy bugs.  Nothing gamebreaking, but I've had characters appear as two characters next to themselves, and I've had a character appear with no skin, only eyeballs and a skull.