This book is a good survey of CPE Bach's life and work, written by a German scholar. It doesn't get into the Schenkerian aspects of Bach's theoretical work; it is more of a standard though scholarly biography and presentation of the works. (Schenker thought the Versuch was the greatest articulation of linear studies prior to his own.) There is good opportunity to understand Bach's involvement with the various communities in which he worked. If you are involved with CPE Bach studies, you have to know this book.
Considering the cost of this book, and the popularity of its subject, it is high time for its reissue!