The book is nothing like the musical.
I just thought I'd give everyone a heads up in case they're thoroughly in love with the musical and don't want to read anything that deviates from it -- even though technically the musical deviated from the book. I read a few reviews where the reviewers were disappointed because the book was so different. That being said, while I'm a fan of the musical, I have never been 100% in love with it. In fact, I prefer the book version.
The book holds a much more complicated relationship with the reader. There is more going on in the plot, there are more plots in general, and it is just over-the-top, gothic horror fun. I am surprised by how much I enjoyed reading this! My only problem with this story was that the writing felt juvenile at times and it often made the already-ridiculous dialogue that much more ridiculous.(However, it should be noted that that could have been Leroux's intention.)
What struck me the most was that this was a re-telling of the Persephone and Hades story from Greek mythology -- and it was a solid re-telling that added more depth to the story, making it more complex. I have seen the movie adaptations of the musical, I've seen the musical itself on Broadway, but never have I connected the dots so clearly as when I was reading it. The lake to the Phantom's house is the lake to the Underworld. This underworld is where the Phantom (Hades) dwells and he goes to the upper world to capture the beautiful Christine (Persephone) to make her his. What impressed me was that there were flowers in the Phantom's underground chamber. Persephone loved three things: sunshine, laughter and wildflowers
Although all the characters themselves felt sympathy for the Phantom, I never once did. It was hard for me to feel sympathetic for a sociopath, which is exactly what he is. I know there are many readers who love the Phantom, but even in the musical version where he is presented as a much more sympathetic character, I could never bring myself to like him. This may have also kept me from completely enjoying the novel.
Either way, this book is very interesting and I would recommend it to everyone. You may love it, hate it or feel ambivalent about it, but I definitely think it's a book worth reading once in your life. It is a very fun ride with a completely wrapped up conclusion.