The last couple of chapters, in which Lewis deals specifically with "pain" (and "animal pain") are far less compelling than the opening chapters in which he establishes the fundamentals of natural law and moral order. This is a brilliant line of reasoning, similar to the argument early in Mere Christianity, but better articulated here, I think.
The Problem of Pain ranks in the Top ten percent of non-fiction
C.S. Lewis's book, Miracles, is similar in scope and dimension to the Problem of Pain.
While I was listening, Vance did so well I often thought I was listening to Lewis.
The Problem with Pain no Problem
Christians will appreciate Lewis's apologetic approach the most.
Christianity is often questioned about how, if God is good, can we live in a universe of pain. It's a difficult problem to answer, but Lewis gives some interesting insight and thoughts on this question.
His arguments may not be correct, but do give reasonable thoughts with which to approach the problem and try to gain some understanding in the universe. It's worth considering for anyone interested in this problem of pain.