Well done!
Mixing and sound design isn't my area, but I can say the composition is nice! You might experiment with varying the harmonic presentation occasionally to spice up the sections where there isn't as much happening in terms of melodic lines. For example, arpeggios/voicing/instrumentation, etc. Just a thought, but really it's quite a well thought out piece, keep it up!
Gustav Johnson
p.s. now that I'm listening a second time, I hear that you did what I just mentioned! It's a little hard to dig out of all the sounds going on. It's so cool, find a way to spotlight it! :)