I like the subject and the grass gives a great feel, but the highlights on the face seem to be a little much. Maybe if the shot was metered on the skin it would have a better light.
Back to comment: A lovely girl but sorry but this is more of a candid photo than a portrait in my opinion. As for the image itself, the focus around the girl's eyes appears to be a little soft. Did you remember to sharpen the image after downsizing for the challenge? The image also appears to be a little flat looking (washed out). Maybe a little tweaking with curves or levels in posting processing would help.
It looks like you have a semi narrow dof which would have been fine if the focus was more on her eyes. It looks like your focus is in the grass between her face and her arm.