This is really neat, but I agree with the other commenters that said her stance was off. Different parts of this image work beautifully individually, but together they look odd. Sure, people can bend over backwards while standing, but can they bend over backwards like that while skating? While I do love the perspective on her legs, her left leg is moving away from her at an angle (compared to her spine).

Also, her hair seems to be a solid block that's moving forward/to the side, despite the fact that she's (I assume) moving forward.

All the individual parts look fantastic, though.

Anti-aliasing would do some incredible stuff to these girls. I really like the eye-dither, I think it gives them character, but those stripes on her skirt look grainy and unfinished.

Congrats Kenpokis! The frame pulls it all together, and I love what you did with the clouds. :D

To me, the reason why you've kept the second one is because he's looking at the viewer. Try putting the eyes (pupils/iris, anyway) of the second one on the first one and see what you think.