This is a pretty good book, but I wish I'd read Jane Eyre before I started it. A good chunk of the story depends on being familiar with Jane Eyre, and so not having read it, I had to find some online Cliffs Notes-like site to get the skeleton of the plot.

It's still really fun and entertaining, and there are many many other literary and artistic references throughout the book, as well as references to all sorts of SF/F standbys such as vampires, werewolves, time travel (and time paradoxes), demons, and more. It's pretty much overflowing with ideas, which explains the plethora of sequels.