Personally, I rather enjoy the mix as a whole. The vocals, while the majority seem to be taking as reason to dislike the arrangement, I actually rather like. Perhaps it's because I can hear how it will progress in future songs, or perhaps because the tone actually has that feel that she doesn't want the other person to leave, an almost sorrowful and longing feel. It's not a feeling one can get as easily with technology-enhanced vocals. Let them be "flat, off-key, nasally, shaky," because it sounds perfect that way with how it's put together.
As for the instruments, well...I really have nothing to say aside from I like them. I look forward to hearing more from you both in the future.