Great, The voices really pulled me in...
The voice in the beginning, the Guy-girl one, sounded a little weird, but I like the "female" male vocal. I particularly enjoyed it around 1:50 to about 2:30 ish, the voice there was nice.
A lot of time when music like this is done with vocals you can't get them to sound right, I think you did that here and I can't stop listening.
I'm no music expert, but in my opinion this is a great piece.