The best part of the book are chapters 9-12 (Ninja Training). I would expect most of the book to be at this level and with this kind of elaboration. The rest of the book was too easy or too complicated.
I have expected more from the book. Differences between old IE browsers and W3C compatible ones fill most of the chapters. Authors argue many times it is more important how to do things than what actual examples, but I would prefer something more interesting.
Good as a rehearsal for advanced programmers