The origin of the book lies in the author being invited by the Inter-Varsity Fellowship to write a book on the moral difficulties found in Scripture. The last chapter was to deal with the question of everlasting torment. When he came to this chapter, he found that he could not answer the question satisfactorily himself. The chapter was, therefore, omitted from the book. He then set himself to study the subject, and the result was that the last chapter was expanded into the present book and the question answered in a different way from what he had first expected.
This short volume, almost impossible to find outside of seminary libraries, has its ups and downs, but it gives some good arguments for the annihilationist/conditionalist view of Hell that aren't find in a lot of conditionalist defenses. For this reason, it is a shame that this book is so hard to come buy (being too obscure to be republished but too new to be public domain).
The biggest weakness was probably Guillebaud's failure to clearly explain that the annihilation is itself the punishment for sin. It is not the case that sinners are fully punished for sin at judgment, and then are destroyed. Whatever the case involving conscious suffering that occurs, the ultimate payment for sin is the destruction itself. This was not made clear (or perhaps Guillebaud didn't even see it this way, but he should have).
All in all, it is useful, though not the greatest defense of the biblical view of Hell (which is good, since this book is not easy for most people to find).