The first time I read this book, I didn't understand it. It was confusing, almost contradictory, and absolutely nothing was what it seemed - and I loved it. The multi-faceted characters were wonderfully portrayed, and it was brimming with that Diana Wynne Jones magic that pervades every one of her books. And, of course, I fancied Mordion instantly.
I'm pretty sure I understand it slightly better now, but on every re-read there are quirks, plot twists and surprising realisations that I'm sure I have never seen before - certainly, it's a book that demand several readings to be appreciated fully. The non-chronological structure, rich mythological references and multiple confused identities might in any other book make for a tedious read. However with Wynne Jones's magical flair they make this tale even more full of wonder, and it sparkles even on a baffling first read.
If you simply enjoy reading a book once, or switching your brain off while you read, this isn't the book for you, but if you happen to be a fan of 'challenging' books, or love to think while you're reading, or even just enjoy rich fantasy, I would say this book is an utter must-read. This book may be more complicated than some of the others, but it is my favourite Diana Wynne Jones book, and an essential for all fans.