I was recommended to read this book when I started Yoshinkan Aikido last year. Regardless of how interested in aikido you might be, this is an amusing, at times fascinating, depiction of Japanese martial arts culture from the perspective of an outsider. Yoshinkan Aikido is a pretty small world it seems, and some of the characters in this book, although sometimes given a kind of fear/awe-filled celebrity by Twigger, are likely to cross your path if you take up the art. Robert Mustard in particular tours quite a lot and attends seminars internationally.
I have read other reviewers say that the book is boring and repetitive, but I didn't think so. The characters were quite funny (especially Fat Frank); the sports angle was well done - not too much triumph over adversity, or at least it's not cheesy. I suppose as a sports book, triumph over adversity is kind of the point of this: Twigger begins the book describing how he is a soft, unfit, bookish type who wouldn't know what to do in a fight. He then begins training at Yoshinkan style Aikido with his flatmates and they quickly become hooked on it. Twigger decides to enrol on the gruelling 'senshusei' course, and much of the book is concerned with his struggles. (The senshusei course is a one year intensive programme of ascetic aikido training taught to members of the Tokyo Riot Police who already hold black belts in, I think, kendo, Judo or karate. Foreigners train separately.) After tolerating a year of daily humiliations, pain, bloody dogis and toilet cleaning, Twigger finally attains his shodan (black belt).
Even if you're don't care about sports or martial arts, give this a try. You could ignore the stuff about flipfalls and learn something about Japanese culture and poetry. I learned that Japanese food is apparently not very good. I like sushi though.