Hello! I'm new here, thought I'd add some thoughts... As a violinist, technically the writing is good, all playable. The only thing is, as a composer, my opinion is that the piece lacks strength melodically. I think it would be important for you to study cadences (how to end phrases) in scores by the great composers, and just generally which steps of the scale like to resolve to which notes (if that makes sense??), to develop an elegance of movement and phrasing which sounds more refined. I will be brutally honest - this piece sounds a bit like a technical exercise with lots of scales and arpeggios, but weak thematically, didn't personally find any memorable melodies to it.
Apologies if I have been harsh in my critique!
Regards,
Zeb.