Haha, first time as a critique...first up, I'd like to say that I rather like this. It's not overdone with crazy colours, it's nice and simple. The overall structure of the pony it well done, although the bat wings are incorrect in the way they are drawn. The fin like parts should connect with the body. The pose could've been a little more dynamic, but well done in the sense of positioning.
I can't give the points for originality, considering it's a request of another persons character, but it's original in the fact that it's your own style, and that can't be ignored.
Your technique is a little off; you still need much practice, and it didn't have much impact, but it is easy on the eyes and still rather well done.