Book is way darker!
Movie is pretty vague comparing to the book. While the book is much more extreme in all elements. If directors like Pascal Laugier were on this project, movie would have that really dark tone and bad smell of the book. Scene when 3 woman taking a shower in the rain, is the single one positive scene from the whole book and made a great emotional impact on the me. While in a movie is just another scene to fill its length.
Women with the glasses has much more deeper character in the book.