I have found a lot of Kakuro books that are just not that challenging, or books that have 125 easy puzzles and 25 hard ones. I like that this series provides a consistent gradually increasing challenge.

I have purchased quite a few books of Kakuro puzzles and this book ranks up there with the best. The puzzles are large 13X22 columns and rows. I enjoy large puzzles and this book contains 150 of them. The puzzles are difficult and it takes a while to complete each one but that's part of the fun!