My rating is based mostly on personal taste. The book as a romance is great but I was left unsatisfied with unsolved and unanswered issued and conflicts on the book. Like, will the created world forever be dependent on a book?
I do not mind putting down a book with ending where the H and h is still facing troubles as a couple. What left me unsatisfied with this book is that the created world of the story is so unstable that instead of being happy for the H and h (and the rest of the great characters) at the book's end, I was left thinking they are better in real world than where they are.
Like I said my rating is purely subjective.