I love it. I think the bottom of the twister is too dark and the edges too smooth (like alk said), but very very nice.
Also, the horizon looks a bit funny to me. It's just that the clouds are so crystal clear way off in the distance. I think you should either blur them, or wash them out; like give them a grey haze to them.
I am not sure. That is just being nit picky though, it is really a lovely piece.
