Janne,

this is a very interesting and mournful song... there is an eerie quality to it that is enhanced by the vocaloids. I weigh in favorably on the choice to use them.

Another reason is that your melody is innovative and I'd guess that might make it difficult for a human to sing, but a vocaloid can do whatever you prescribe. VERY interesting melody! Without the surgical precision of the vocaloid's voice, I think a human might very easily sound out of tune singing certain parts of this song.

The instrumentation is very delicate and minimal, but also very beautiful and tasteful. Good selection and arrangement of real tracks.

I like the recurring motif of vocaloid harmony, and the interesting chord progression. Everything about this song seems quite original and fresh to me. That's quite an accomplishment!