Good book, most of it is clearly written and illustrated, including short exercises and quizzes that I think are effective. Towards the end it feels a little rushed and abrupt.
My biggest complaint can't be attributed to the book itself so much as the format. Much of the content really needs to be memorized via repetition and practice; the book isn't oriented towards getting everything into long-term memory. Few books are or can be. So plan on making flashcards or reviewing sections of the book many times, rather than only reading from front to back (as the author does mention).
Even better, if you have an iPad, look into apps such as Waay, Tenuto, and Earpeggio, which are extremely helpful for learning and memorizing theory, reading staff/notes, identifying intervals, and much more.