Really really like this track. I feel it's a tad to long though. The first half is excellent but I think the 2nd half sort of trails off on some different ideas that don't benefit the rest of the song as much as they could.
As for mixing I would bring up the Piano chords in the first 30 seconds a tad bit, the chords really bring out the melody and I think bringing up the piano in the mix would emphasize that. After 30 seconds it seems as if everything is a little more even, I can hear the piano better.