I don't like the driven guitar, but that is just my taste. The melody is fine, but i don't like the tone.
as for the vocals, my opinion is that you don't seem to set it on the mix because when he stops singing there is "silence". and it sounds almost unnatural stop and unmusical. Note that the parts where you have the second voice it sits in there a lot more confortable.
My suggestion? use a delay in the main voice, perhaps 1/8 or 2/8 of the tempo on a different track( all wet of course), then set a low pass somewhere between 800 and 1k to take away the clarity. This should give the voice appear bigger and the cut when he stops singing a bit more gradual. Think of it a a tail of the sound but not reverb. Then of course set the volume of the delayed track to sit a bit behind the main vocals.
Another think you can do, complementing the delay is using a side chain compressor on the delay track, using the main vocal as a side chain input. Doing this the delay track will lower it's volume while the singer sings and get up inmediately when he stops providing the same tail but leaving the singing part more alone.
Side-note: I would also use a very light de-esser on the main vocal track, but veeeeery subtle.
Of course this is my opinion.
Federico.