First of all, the author writes a lot, but says few things. This becomes annoying. Then, another thing that I didn't like is that, after reading 150 pages, I couldn't tell anyone what XML was about. I had to go to www.w3c.org, spend some time reading some XML specifications and then come back the to the book. Only after I did this, the book made sense to me... But I bought the book in order to avoid reading the W3C specifications. I wanted something "lighter" than the standards...
Probably the book has some good things, but I don't want to mention them here because I am too affected by the weakness of this book.
My advice: if you want to read a book about XML, try another one!