First of all, welcome to YC
Now. about your piece.
Melody: What I really like in it is that you have a pretty good ability to write MELODY. This is something many people do lack, but your melodic line is really good.
Texture/figuration: As PranoidFreak pointed out, the left hand is pretty tiring for the ear, and you should definitely refactor it.
Harmony: You have good sense of harmonic progressions, but one thing you should not forget is that along with main chords there are inverses! My ear longed for inverses throughout the piece. For example, in bar 6 and/or bar 8, I wanted to hear an E-flat in bass. Really, if you enrich your whole piece with a lot of inverses, it will be much MUCH better.
Form: If I say that this isn't a sonata form, you'll probably point me the two main subjects the development section, the reprise,etc., and will disagree with me. But remember that the form not only means placement of themes/sections in time, but also the placement of climaxes. In sonata form. I can't say why exactly, but this didn't seem a sonata for me. This is really more a prelude. Never mind though
Voice-Leading (or whatever the English term is ) : You have qiute a few (hidden) parallel octaves and fifths in your piece. With richer texture, this don't matter, but taking the tempo and the thin texture into account, these really punch me in the ear. Examples include bar 26-27 (Dflat-C) 27 (e-natural - g), bar 75-76 C-D and many others, Consider working them around
Beginning: I don't really see the purpose of the first two bars. Consider either removing them or changing them.
Ending: The B-natural in the one-but last measure does very bad things.for me. It seems really artificial. Just have a G with lengh 1/8 or do something else. The B-natural doesn't belong there
I don't want you to get the impression that all my review is critique, no, it is not. I just pointed out some of the bad things (in fact I may well be wrong,cause I don't have musical education). But the piece overall is very promising. Looking forward to listen to the reviewed version!
That'll be my two cents