This is the best book about solving cryptic crosswords I've seen since Don Manley's "Chambers Crossword Manual" appeared in 1986. The author is supremely well qualified for his task. He has been setting Times puzzles since 1976, and was the paper's crossword editor for five years. He has also competed (like your reviewer) in the final of the Times Crossword Championship, so understands both sides of the contest between setter and solver. His work as a psychologist, specialising in mathematical education, gives him insights into problem solving, which he exploits well.
The book is quite short (136pp) but covers a lot of ground in that space. There are hundreds of sample clues (often very celver ones) scattered through the text. The potential problem of attempting to solve them in isolation is alleviated by the "First Aid Section" listing some checking letters you might have if the clue was part of a puzzle. Answers to all the sample clues are included, including explanations of literary references and the less obvious bits of "General Knowledge" required.
The book is a little short on actual puzzles. Five sample Times puzzles are included, and three tutorial puzzles rather forbiddingly labelled as "Tests". However, there are plenty of newspaper and puzzle books out there.
Like most books on cryptic crosswords, a brief history is included, as well as material more specifically related to Times puzzles, and they way they have changed over the years. These sections managed to include some facts that this reader of crossword-related books hadn't seen before.
Any book explaining cryptic crosswords has to give major attention to the types of clues that are used. This is done elegantly, and each type is illustrated with plenty of examples.
Many aspects of the book agree with my own views - there are plenty of illustrations of good and bad practice in clue-writing, and I was pleased to see the world's sloppier cryptic crossword setters reminded of simple facts such as "an ion is not a charge".
One criticism: Times Books, like their parent newspaper these days, don't take enough care to remove mistakes. So we have a quoted letter to the Times that looks like three lines of unrhymed modern verse (p. 46), the words "themselves, like" with a mid-paragraph line to themselves (p.59), and the statement that words should ideally "appear in the Concise Oxford and Collins English Dictionary, and preferably both" (p. 61). I hope there are no similar mistakes in any of the clues or puzzles.