It seems you have under exposed by about 2/3's to even a full stop. After the challenge, I would try boosting the levels or exposure if you shoot in raw. Perhaps not so much contrast either would possibly work here.
i really like the concept in the photo....the only issue i can find is that the sky is so gorgeous i would rather look at that then your subject.....best of luck
Almost but not quite is my honest reaction to this. It just lacks any elegance os simplicity. I know what you were trying to achieve but the result almost feels as though the tripod had been knocked just before the exposure.