Intermediary puzzlists will find the pleasures of often working at the upper edge of their skills. The solutions at the end of the book are complete enough so that even those who didn't get it right the first time will get aha insights.

The book is well worth its price even for puzzle enthusiasts. Even I knew many of the puzzles beforehand - classics indeed - but the notes in the solutions often add a twist, a clever solution or a human interest point of view.

The age recommendation of amazon.com - 4-8 years - is probably either an insider joke or a typo. I'd recommend this book to people between 14-80 years of age, and even over.