Definitely want the option to mute the PC.
I'm sure the voice actor did a fine job (though I wasn't terribly blown away by what I've seen in the video). The issue is that, as many have said, a voiced protagonist is another little removal of player control.
With an unvoiced protag and vague dialogue topics (a la Oblivion or Morrowind), I could imagine my character saying pretty much anything. Contrast that with Skyrim's specific dialogue options for the player: now I am told this is what my character is saying, word for word. But at least, since Skyrim's protag is unvoiced, I can imagine him saying it in a different tone of voice. That allows me to replay the same scene with different characters.
A voiced protagonist with specific dialogue options is going to be repetitive, and that will likely cut down on replayability for me.
When I get a Bethesda game, I'm in it for the long haul. I make dozens, hundreds of characters. I play the thing for *years*. What sustains that replayability is the way I can re-imagine the character that I create. That re-imagining becomes a bit harder if that character has the same voice every time.