I loved the chordal structure
This sounded like it had a Beethoven influence to it also.
Here is where I think it could improve. Well for one, it sounded very midi, which, although does not effect the music in a structural way, detracted from the overall performance. Since you can play the piano well enough to play this without too much difficulty, I would suggest playing this and recording it on a real piano, or using a nicer VST to play it. That may be out of your control, however.
A Mazurka is a (polish) dance. I was pleased to hear that you accented the 2nd beat of each measure (I hear people accent the first beat when performing Mazurkas sometimes, which isn't correct). You have to keep in mind that Mazurkas are traditionally lively, though. I can't picture many people actually dancing to this, although I love the chordal structure of it. I suggest speeding the tempo up slightly, and rethinking your first section. Although I liked the tonal instability at the beginning, I don't think it is a good way to begin a Mazurka.
Listen to the Mazurka in Bb by Chopin for an example of a very lively Mazurka, but with a tonally unstable C section.
Remember, all of these are my own opinion and others may disagree with me. But if this was my piece, I would aim for a more 'traditional' (if that is what you would call it) Mazurka.
Very good work though, I am impressed by many aspects of this piece!
5/5