With the Howard Kasschau Piano Course, you actually have the option of two books to get started: the preliminary book and Book 1. The preliminary book is aimed at a young beginner, while the other book, Book 1, is meant to be for everyone else.
If Book 1 is used as a beginner’s book, then quite frankly, I don’t like it at all because it presumes too much knowledge and it gives the piano student no time to get used to playing with each hand. However, if it was used as a follow on book from the preliminary book, then I think it would be very useful.
As far as the preliminary book of the Howard Kasschau Piano Course goes, it is a common sense, logical and well explained book. It introduces new notes and new concepts gradually and although it is designed for the very young beginner, I think it would be excellent for any beginner. It would definitely be a suitable piano course for someone who was retired and were embarking on learning to play the piano.
Not that I think that it makes a difference, but this series of books have been around for decades and was first published in 1959. The presentation of the book doesn’t look if it has been updated, but I don’t think that is necessarily important, unless you are specifically looking for a modern aesthetic.
The preliminary book is a beginners piano book that I have used personally with teaching my own students and while it is not my favorite, it certainly covers the fundamentals that are important to teach.
If there was a flaw with these piano books, it would be that there is no opportunity for students to start doing some basic written theory. Some people might see this as a benefit because the student doesn’t have to do any written theory at all, or a teacher might prefer to teach the theory from a different, separate book.
For me as a piano teacher, I won’t use these books regularly as I think the price of the preliminary book is too expensive. I can’t speak for any other place, but for here in Australia, the preliminary book of the Howard Kasschau Piano Course is too expensive and that there are other equal quality piano courses available for a lower price.
Despite the price here in Australia, I would still recommend this book for someone who learned to play the piano years ago as a child and wants to return to playing the piano in their retirement and they are looking for a refresher. This book would be excellent in this situation because it would either be the same, or similar to what a person learned as a young student. The familiarity could help trigger memories and therefore knowledge that was presumed as being lost.
Overall, I think that the Howard Kasschau piano course books are very logical and thorough. It teaching the basics of playing the piano, especially if the preliminary book was completed before tackling Book 1.