1. Overall, it is a good art-piece. But a few artistic refinement thoughts for the future...
2. Magic... Seeing this and the previous works with Starchaser, I would suggest changing the color of her magic to something more contrasting. As is, Starchaser's magic blends-in too much with her coat and hair.
3. Angle Portrayal... It is an educated guess that you angled Starchaser to mimic the shooting stars of the background as well as her Cutie Mark. Unfortunately, it also makes Starchaser look like she is tumbling down a flight of stairs as much as than pseudo-flying/-diving. Either the pose could stand to be adjusted to make it look like she is diving, or perhaps have Starchaser in an opposite angle, she is rising up to the skies "to chase the stars."
4. I look forward to when you portray Harmony, her Cutie Mark, and "special talent" theme(s).