This book is a great encouragement to people who wish to live a life in the pursuit of truth. It reminds one that living a life with much reading and writing is a struggle. There are countless temptations to quit. The the same time, it is a noble way to live, which brings us many joys and ultimately brings us closer to God.
Sertillanges offers some excellent advice. The only one I feel disinclined to take is his one on concentrating on only a small number of books. (His earlier advice to gain a broad understanding of various fields seems to contradict this, but he leaves finding the right balance to the reader.) This seems to make more sense if one is a Thomistic philosopher than, say, an intellectual worker in English Literature. Though, I suppose that one can specialized in a particular author's works while having a broad understanding of other writers' works.
Perhaps his best advice is to remember that an intellectual is supposed to be a complete man, so he cannot neglect proper human things in his pursuit of wisdom. That would imply wanting knowledge without applying it! He takes inspiration from St. Thomas Aquinas' advice over how to lead an intellectual life and expands on them. His style is simple, forceful, and profound. This book felt as much a page turner as certain thriller novels. One cannot recommend this book more highly for those who want to engage in the pursuit of Truth.