I like the way this work has a feel of classical art. The choice of the Lute fits perfectly into that theme.
To me the key to this piece is the fact the horse to human transformation being hidden behind the instrument. I am assuming that was on purpose. The fact that you are painting a centaur in not immediately obvious and it adds to the impact when the viewer realizes what is being presented. That turns what would be a mundane scene into something that catches the eye.
If I was to make any improvement I would have placed the fingers on her right had to actually be in a strumming position.
Very nice work.