I own Book II and have used the TheoryTab pages a few times, so these comments are really just based on those products and my impressions.
Overall the book is really great. I jumped straight to Book II as I already had an understanding of the Book I concepts mostly, and the Book II advanced topics have been very helpful and informative.
My biggest complaint is with the musical samples and examples in the book. Particularly the topics that involve harmony.
The samples do not highlight the harmonic makeup of the song. The melody gets in the way. I understand this is showing how the song works as a whole, but in chapters discussing harmony all I want to hear is the harmony. I dont need to hear the melody laid over the top. I want to hear the difference and inversion makes, or whatever the example is showing.
At least in TheoryTab we have the option to turn the melody off. Can you please consider adding this option to the Books
Thanks