This is really neat and makes me wonder what the model is thinking about or looking at. I'm surprised it scored so low. Pose is good.
What I would do to improve it is to crop quite a bit off the sides to put the focus more on the model's head. The blinds are begging for attention and it's slightly blown out on the top end of the blinds. If you set exposure for the bright background you may have gotten the silhouette without the blownout area.
I meant to leave a comment shortly after the challenge winners were posted. Two small suggestions. First, try cropping off the left window entirely. Second, bump up the contrast a tad to make the silhouette effect stronger. Give it a try and let me know what you think.