Depends ...
I mean sure, voicing can add (or ruin) a lot ... sometimes its almost unbelievable how much.
But i grown up on games like Final Fantasy (7,8,9), where never was any voicing and those characters allways seems so much deeper to me than some of today fully voiced protagonists. -_-
So i also presume its not miracle that can save everything on itself. :-/
Good voicing for companions is great ...
Good voicing for pre-set protagonist is also great ...
But voicing "player-created" character? :-/ Nah ... there is too much that can go wrong, i prefer such characters to only have some barks as they had in DA:O.
I still dont understand why cant we change Race for our hirelings.

Lets us play Githyanki as racist as they trully are!