This is a collection of 114 life-and-death problems, divided into elementary, intermediate, and advanced sections. I haven't had time to read it very carefully, I'm afraid, but my impression when I worked through some of them is that they're well chosen. My impression was that the elementary problems were suitable for strong kyus while the other two sections were getting more into the dan-level. Now that I look at it again, however, I suspect they're not quite that hard: strong kyu-level players would enjoy all of the book, and middle-kyu players would get something out of the earlier problems.