Final Sketch for Udolpho

I am working on the last of 10 illustrations for The Mysteries of Udolpho by Ann Radcliffe. Some of them, I have recently put up on my website, and I am very pleased with the project as a whole. I am now working on the final image, which will probably be the cover.

I have here a rough greyscale workup of my plan, and I would like some constructive criticism. Does the castle look imposing enough? Does the figure stand out? Is the ground believable

? How well does the contrast work? Does anything stand out as glaringly wrong? What would you change or add?

Thanks for the comments.