A beautifully written history book. Be warned: if you go in expecting a straightforward story with a linear plot, character beats, etc - you may be disappointed. This book is full of fun footnotes, wonderful description of whimsical magic and fairy logic, and so much interesting historical concepts. After finishing this book I felt like I had some sense of what historical England felt like. But the same way you don't really learn the end of George Washington reading a history book, you may not get a satisfying ending here.
If you'd like something like that I highly suggest the television adaptation, which I hear does a good job of condensing and focusing the story here. But this does not mean this book is bad by any means. It's just a different beast.