Hah! Got a sample for you guys.
It sounds just like I suspected. Don't quit your day job main singers. Computer voices still sound resonated at certain pitches and words aren't clear enough yet.
HOWEVER, it is impressive how far computer voices have come to actually sing and in chorus mode too, I've heard one. I myself will probably buy it because the voices I need should sound like they are going through a vocoder anyways.
For an understanding of what Vocaloid is, check out:
Sample of Vocaloid 'amazing grace' (Main singer plus humming)