Nice idea and the composition works. I see where you're going with the selective desaturation but perhaps the post processing might need tweaking or maybe just going another route with it. The shot itself has promise.
Tough harsh lighting conditions. Not sure of the partial de-sat has helped or exacerbated a slight sense of over-exposure. Otherwise a cool, well composed shot.
Would like to have subject show some eye contact with the camera. Also it looks like your highlights are blown out, I assume that this was taken around the noon hour. Unless it is a cloudy day try to avoid this time because it gives you harsh shadows. Go for in the morning or an hour or two before sunset. Great idea and I love the lines that the trees make.