That's my point, they are really keeping the voice secret, maybe to stop a huge onslaught of pre release complaints ??
I rekon it will be the stock phone voice and eventually everyone will get an expression face, they will use China to perfect expression and roll it out to the rest of Cortana but in a more western style
They have got to differentiate Cortana from the opposition, a clever voice is not enough, and it has to be effective on large screens, a blank screen with a circle on a large display is uninspiring !
I said it before in another thread, Xbox has ears and eyes but no face