I have two daughters and their piano teacher recommended this and the first book to us.
My first daughter isn't that keen on playing but enjoyed this book a lot.
The revelation was my second daughter who loves the piano so much it has become her obsession; for her, this book was ideal - the funny but to-the-point illustrations and simple text allowed her to use it (at the age of 7) effectively to teach herself.
The progression from tune to tune is clear, logical and engaging and made complete sense to her and gave her a constant sense of achievement as she moved through from song to song. And all of this was with limited input from us.
Really the best beginners piano book we have seen and for the self-motivated kid, the perfect choice.