Aikido is probably one of, if not the most sophisticated of all martial arts. It challenges a student both mentally, physically, psychologically, and spiritually for a lifetime. Richard and Kathy Crane, both full time Aikido instructors from New Jersey (and both holding a 5th Dan ranking in Aikido) do a phenomenal job supplying the reader with a wealth of information on Aikido. Empty hand techniques (Taijutsu,) weapons techniques (Buki-waza,) and Aikido principles are all put forth in a clear and concise manner.
This book is not another one of those "Hollywood" type martial arts books that teach you how to beat up everyone on your block. Instead, the Cranes are teaching a true Japanese Budo, or Way, with a great deal of care and insight. The physical techniques of Aikido are tools used to help the student develop and improve themself physically, as well as mentally and spiritually. Aikido Senseis (teachers) like the Cranes are excellent examples of what all martial art instructors should be.
There are other excellent "series" of instructional books on traditional Aikido available, particularly those by Morihiro Saito Sensei (9th Dan,) but this book, Aikido in Training, is the best "one stop" Aikido instruction book you could ever have, period.