Ruby Slippers reminded me very much of a story in lines of The Yellow Wallpaper, or The Awakening - it's not so much a story as it is a study of a psychological disorder. In the case of Ruby Slippers, that would be a dissociative fugue. In a fugue state, a person will forget their previous life, developing a form of amnesia. They'll create an entirely new persona, and occasionally wander off and create a new life for themselves. Fugues can last weeks or years depending on the case. This story is interesting, in the way it compares the fugue state to what Dorothy from The Wizard of Oz experiences.
They story itself was a bit difficult to follow at times. It was gorgeously written, don't get me wrong - but there would be frequent characters shifts with no warning. While it wasn't impossible to figure out who the new narrator was, it was a bit disconcerting, and took a few minutes to put everything together.
As I'm coming to expect from Sophie Nicholls, the word choice was wonderful. The book read like a very long poem, almost.
I enjoyed the parallels to The Wizard of Oz. Some of the most descriptive scenes in the story where the ones where Elena broke away from what she was doing to picture a scene from the 1930's film. Nicholl's word choice and way of description brought a whole new level to Dorothy's reactions.
Between The Dress and Ruby Slippers, The Dress is definitely the stronger story. But Ruby Slippers was published before The Dress was. It feels almost like an experiment of Nicholl's writing style. And I've got to give Ruby Slippers credit for leading to the awesomeness that was The Dress.