chrisj, welcome to the hot seat. (you sorta did this to yourself by mentioning it)
your piano treatment is really nice. right off the bat, i want to listen a bit further to see how things develope. you used the sharp attack of the piano to your advantage in a nice way. the bottom end of the piano is pretty thin, but can be excused for the moment.
the vocal comes in. this is when i would turn it off. the vocal effects don't match the piano. 90% of the listeners (educated in audio or not) want a solo piano and vocal performance to sit in the same space. mentally, they are visualizing a guy at a piano, playing and singing at the same time, i.e. elton john. i think we all agree on this.
so, with that in mind, your vocal treatment, doesn't match the piano.
the plosives on the vocal mic are distracting. roll off the vocal mic until the bottom of his actual voice rolls off.
i want to hear that vocal compressed hard to give it the same edge your piano has. visualize these two elements as one. marry them, literally. think of all the stereotypes you have a piano playing singer and ldo not hesitate to play into them.
if the piano has a sharp attack, make his vocal identical.
in songs like this i will pay closer attention to lyrical content. if the song has a darker lyrical point, i might make the mix dark to instantly put your mind into that place. OR, i might make it very bright and smooth to keep a person from killing themselves when they really dig into the lyrics. you have to focus a mix like this around the only elements you have....piano, vocal, lyrics.
if you have time, i'd like to hear a recall, i do not expect it, but it would be cool to hear how my comments shift your focus and see what you might do with it now.
i'm going to do two more of these in the next few days.