The first thing to say is that this book will not teach you Japanese.
Anyone who has ever attempted to learn Japanese will, however, agree that the hardest aspect of studying this infuriating, endearing language is kanji, and the main trouble is remembering how to write the little beasts. What this book does is to systematise the mnemonics that we all invent for ourselves - "thing like a ladder, box lid, lantern, child, camp-stool, moon, mouth, twiddly-thing-that-means-motion". Then the author combines these, or encourages the student to combine them, into 'stories', which you are supposed to visualise, thereby remembering the writing of the kanji. And it does work, up to a point.
Other reviewers have commented that the book is very, very American, which sometimes poses difficulties. Several of the stories are concerned with baseball, about which I know nothing; there are numerous references to Bible stories and the doings of Almighty God, which is rather off-putting; and "a moose head hanging on the wall of the den" is not the first image that would come to the mind of an urban Brit. There are some strange choices, too - why the familiar standing bowl of rice that forms a part of so many kanji to do with eating and drinking - taberu, nomeru, musume... should become 'halo' is beyond me. So I am not sticking faithfully to Mr Heisig's 'primitives'; I am using the book more as a starting point for creating my own system.
The book does not include any Japanese readings of the kanji - each one is just given a 'key word' meaning in English, some of them rather wide of the mark, I feel. I gather that there's another volume that teaches the readings, but I will probably stick to my kanji textbook for that. Heisig warns that you should not use his book whilst studying kanji the conventional way, which is quite weird - who, other than a student of Japanese, could possibly want to Remember the Kanji?