As RF Said, the piano is too dry. Could really use some reverb. Really enjoyed the melodies in this actually. I didn't feel like the melody fit together with the chord progression at 1:20. I do think this track is a bit plain and lacks some other layers to make it really interesting. I do think you did a good with what you have atm though. Really liked the strings you added.
The piece fits the starry sky in the art in a decent way, though I do think it would be even better with more layers. The transitions are decent, though I do think there are more creative ways to do them.

Overall the mixing is not too bad, but the chord parts of the piano and the piano lead should be mixed better together. Kinda clashing with eachother atm.
There's a lot of potential in this track but it's lacking some things.

Arrangement: 3/5
Sound Design: 2/5
Mixing: 3/5
Art Relevance: 4/5
Overall: 3/5

RealFaction must be having a bad day, I LOVED IT. Yes, the piano could use reverb but the song itself was beautiful. Don't be brought down by that other comment :)