Oh my, I really love the colors and how they contrast and blend! I also love Twilight's determined face and her little jumping pose... Actually, the pose and the tree she's leaping over is probably my favorite part, it just makes it feel dynamic and alive.
And now I'm rambling! Really quick though, I love the moon rising out of the lavender/misty background. It kind of gives of this mystical feel... I just love everything about this xD