This book is not for the beginner or the faint-hearted. WHilst it got me up and running with the ideas behind XML, you only have to look at the thickness of the book to be intimidated!
It is not the sort of book to cuddle up to for a bed-time read. It is also not really recommended if you know nothing about XML. It is recommended if you need a reference book.
It would seem to me that if you asked the author to write 10,000 words about the colour blue, he would be able to do it without breaking into a sweat.
Every aspect is covered. The detail the author goes into can either be praised for being thorough or criticised for being too verbose. What happened to the idea of telling you what you need to know and leaving out the bits you don't need? The huge section about Unicode did for me. I read about one inch, every word, but when he started on Unicode, I found myself less and less enthusiastic to continue, to the point of putting the book down.
Buy this book if you want a ference book. Don't buy it if you want an easy to follow step by step guide to XML. There's bound to be better books than this for doing that.