As I listen:
This is very good. I won't comment on the production too much since it is a demo. It is good though, needs some meat around 100-200hz and a bit less in the vocals around 3-6Khz. The Highs should be rolled off a little more so it isn't quite as airy.
Songwriting is good. The guitars could use some 5th harmonic action
To me, the singer should be singing in a lower toned voice so it isn't quite so "lazy" sounding or sharp. This is easy to do. Add more diaphram air and lower the voicebox and keep it there. When the air comes from the diaphram heavily and the voice brought down a little, it gives the singer that aura of really putting a lot of passion into it AND it will be much easier to hit notes and hold them forever. Virtually every singer I can think of does it like that even if their voice sounds high pitched. His "falsetto" will sound much richer and he'll be able to hit higher notes too.
If you can get the stems, I'll remix it for you out of the kindness of my heart since I enjoy working with audio whenever I can
