This book is written by Walther G. Von Krenner with Ken Jeremiah. Walther has been studying Aikido since the 1960s and runs a dojo in Montana, USA. According to his bio found here he is Hachi-dan in aikido and has studied with Morihei Ueshiba, Kisshomaru Ueshiba and Kochei Tohei.
I will review the book based on the sections it is split into so you can decide if it is something you may read for yourself. I bought the ebook version from Kindle.
The book is split into three parts; Shodan (basic), Chudan (intermediate) and Jodan (advanced). Each part is a section with its own chapters.
Section 1 focuses on striking both from the uke's (attacker) and nage's (defender) viewpoint. The author writes about striking well and with intent. For uke's role he looks at the three stylised attacks often found in aikido dojo; shomen uchi, yokomen uchi and tsuki. He also talks about the grabbing attacks and initiative. For nage's benefit he looks at the first four pinning techniques often practised; Ikkyo, Nikkyo, Sankyo and Yonkyo. He discusses where and why atemi (strikes) are used at the beginning, during or the end of a technique. Chapter Three of this section looks at striking during aikido throws. Kaiten-nage, Shihonage and Sumi-Otoshi are discussed. The final part of section 1 looks at "Putting it all together." The author gives examples of how strikes can be applied to specific examples of attack and defence using pictures. Throughout this section the author references the founder of Aikido, Morihei Ueshiba and attempts to relate sword arts to empty hand strikes. Although the whole section is really about striking correctly as an attacker and knowing when and where to strike during a pinning or throwing technique as a defender, the author offers more than this. He speaks about principles of movement. Such phrases as "The shoulders should never rise while striking.", "Always feel as though you are extending energy from the finger tips and even the elbow joint." and "The basics of stability and correct body movements are the key to performing more advanced techniques." are gems hidden within the text.
Section 2 assumes the Aikidoka has a good understanding of basic striking and moving. The principle of irimi is discussed and defined according to the author. He calls upon principles of Ona-ha Itto Ryu to help describe his concept of irimi. Of course it is only logical that a discussion of irimi leads into a discussion about irimi-nage and that is exactly what happens in this book. Irimi is discussed as a way to dominate an opponent. Keeping this in mind, the author explores aiki and kiai. I'll leave you to read the book to see what is discussed here.
Section 3 delves into the esoteric power of Aikido. Of course there are endless stories of Morihei Ueshiba's power and strength. What the author tries to do is to break down the illusion of mysticism around the founder of Aikido and suggests that there is a definite method of learning and improving this skill. Here the book explores the power of Takeda of Daito-Ryu Aikijujutsu fame and one of his best students, Sagawa Yukiyoshi. Aiki is described as a skill that develops immovability and unstoppable force and not simply "the flow of ki". Tohei's four basic principles are introduced here as a method to develop aiki. Each of the four principles are explained in detail: Keep one point, Relax completely, Keep weight underside, and Extend ki. O-sensei's solo training exercises are also mentioned, especially funakogi-undo and ikkyo-undo. The author stresses the importance of these two exercises in the development of aiki. He takes the point further by adding that having people push on you while doing these exercises will improve your skill substantially. He ends this section with the quote, "The true source of power in Aikido is not within the varied techniques, but rather in the internal training exercises that have been overlooked by many practitioners."
Conclusion. Finally, the author gives a short conclusion summarizing his main points throughout the book. It is a very good synopsis of what is written and I would actually recommend reading this first and go to the appropriate chapter to read further if key points interest you.
So my thoughts overall? I found the book really interesting to read. Having a background in Aikido and what I believe to be some understanding of internal training I liked what I read. However, I am a naturally skeptical man and I have heard some of these terms thrown about (excuse the pun) by Aikido instructors before. Those same instructors didn't really demonstrate any of these principles on the mat (not at least to the level we are talking about here). The author didn't give me enough to be fully convinced he had cracked the internal power thing. I had a search of him on YouTube and there are videos. As is often the case with this stuff it is hard to really know what is going on from just watching someone perform techniques. His martial application of aikido strikes and concepts surrounding this, I agree with. Putting section 3 aside for a moment, the other two sections give plenty for an Aikidoka to work with to ensure they are practising a martially viable version of the art.
If you are serious about your Aikido then I would recommend this book. At the very least it will give you another perspective from which to view the art.