We definitely need to see more brony artists experiment with traditional media. It's great to see someone "paint" an extravagant scene on a computer, but if they were to do the same thing on an actual piece of paper--now that would be something!
From working with watercolors a bit myself, you must have a very careful hand in order to apply it all so strategically and delicately, particularly in the background effects. To be honest, her hair looks a little crazy to me, but I understand that it's a stylistic approach. All in all, this is a beautiful piece and I hope the practice served you well. Keep up the good work!