I'll start by saying I love the song. LOVE the song. The lyrics are great, the structure is awesome. Just... wow.
As far as the vocals, I'm a little mixed on the FX. I THINK (and heck... I don't know...) that what bothers me is a combination of where they sit in the mix (pretty forward, which works somewhat until you get to the 3:34 mark, where they really jump out at you and it's a bit of a jolt), the FX that's on them, and the way they are performed. I think I might like them better if they were performed with a little less nasal presence--this is personal, and technique related though, and may not be easily changed. That said, I like the IDEA of what you're doing with them (including that, short delay/almost low-fi effect), but on the other hand, it feels little like the vocals and the "space" they occupy is too far removed from the instruments that accompany them. It seems disjointed, and maybe a little less extreme version of the FX you're using would help gel everything together a little more. I love the harmonies you're using--they are well timed, not-overdone and add a lot to mood of the song. Really like that.
I also think the arrangement seems to be missing something. I'm not sure what, but it seems a bit sparse in some way--but not by much.
Really like the song. I would never be able to do something like this.
iMac 27" Quad Core 8 GB RAM, OSX 10.7
Steinberg MR816, Motif XF8, Maschine, Cubase 6.5.3 / 7.03. Omnisphere, Stylus RMX, Komplete 8 Ultimate, Fabfilter Total Bundle, Sibelius