Aikido and the Dynamic Sphere is a fine book.
Its use of diagrams does help explain some of aikido principles well. Yet there is so mcuh it can't address that only instruction can fill in. This does not detract from the book , just suggests all books limitations.
The recent series of Aikido techniques here on Fighting Arts.com is also a great reference tool by an exeteremly accomplished aikido-ka.
Aikido is an extremely well documented art.
I've never met an aikido book I didn't love. They show so many different variations on the themes, all of which help express the art more fully.
bushi no te isshinryu