I don't often wish that I was younger when reading a book, though I almost wish I had discovered Malinda Lo right around when I started reading Robin McKinley. Of course, Lo had not starting writing then, so it's a moot point, but I think I would have put this book into my reread early and often rotation. I wish I had time to reread books.
Anyway, Lo does a wonderful job retelling Cinderella (which, I should note, is the reason this is 4 rather than 5 stars. I don't like Cinderella. The book was more than worth it, though) and creating an intriguing fantasy world where, among other things, the fairies in fairy tale are taken seriously as the Sidhe. She writes somewhere in between the fae and the pragmatic - what she accomplishes reminds me of Robin McKinley but her voice is all her own. And what she does with this story is wonderful - she made Cinderella a story I could believe in.