Although I dont know Robert Twigger and even never met him, after reading Mike Kimedas and Nic Mills reviews, and talking to Nic Mills about Twigger I have no aspirations or intentions in reading the book. I believe Twigger didnt train in Aikido before going through the senshusei course. It seems as though he had no desire to become an Aikidoka and this is evident in the responses given by by both Mike and Nic.
Twigger is a writer who travels around the world in search of new adventures and writes about his experiences. By no means is he an Anthropologist. It seems as though he went into the course with a frame of mind focusing on survival and not focusing on learning and self discovery. Im told there is a difference between those who get through the senshusei course and those who "complete" it. Apparently they will not kick you out of the senshusei course, it is just expected that you leave if you can not handle it. Many westerners dont seem to understand this and get through the course and feel like they have accomplished something. Those who complete it are those who actually care about what they are doing, trying to get the most out of it, and trying their best. I dont feel that anyone that hasnt "completed" the course would have anything valuable to say towards Yoshinkan Aikido.
Im just going by what I have read about the senshusei course and Robert Twigger, and what I have learned through those that have known him. I have absolutely no intention of reading the book. The only suggestion I could make is for the Yoshinkan Honbu dojo to have a better screening policy for the senshusei course so they can weed out those Westerners who know nothing of the culture and have no affinity for Aikido.
Have a Great Day!