Nice ideas here and there, but track feels very emty. Piano is lacking of velocity variations, humanisation. Same in strings - they need dynamic and volume automatisation. Even with good orchestretion without those details track will loose many points. 

Good overall orchestration! People have already described the main problems in the comments: the fullness and variety of tools. And so - a beautiful job

I think with some more instruments and maybe some instruments in lower registers for nice bass sounds this could be a lot better.

Oh, this is nice! Big fan of the orchestral section in particular; flows well and is very evocative. Ending on the piano to bring it all back around is a great idea, too. Super solid score, good work. :)

The idea itself is very good, and the track isn't bad, but I'd suggest you to use more instruments and/or more variative melody. Also, try to play around with instruments' note velocity and panning, might help to achieve more depth of the sound.