Here's my unbiased and sincere opinion, hoping that it could be of help for others.
I'm learning a lot from this book. It's great expecially for learning to correctly read notes duration in written music; thanks to the "rhythm patterns" approach. You have to listen to some rhythmic patterns, then move (your leg, your hand, whatever: using also your body helps you to remember and learn - I know this because my girlfriend is a teacher), than move and echo to the rhythm, and then do the same
reading the notes as the last step! Very effective.
The book approach is gradual, but it brings you pretty far while being for beginners. It begins with tunes you can play with one hand and the easiest rhytmic patterns and it step by step guide you to discover more complex rhytms and more complex notes (the highests!).
It's also full of tips for teaching to kids; and overall one can feel the passion for teaching and the experience that the author put in.
The only backside I could personally find of that is that the recordings are all done with quite a lot of reverb; while I personally would had preferred more to listen the tracks as I
could play with my practice in normal life; I mean, to have a sample to strive at while improving.
Overall: highly recommended for any beginner. There are plenty of tips both in the text and in audio parts. The approach is slow and steady, every units have advanced activities (like playing by ear) and the voices are great

.
That's all.