For a divinity scholar to dislike DeCaussade is rather like a film buff's not caring for Citizen Kane - it just is not done, since it is universally considered a great classic. I would recommend this book as a means of seeing how a popular spirituality, in marked contrast to Jansenistic or eternal Pelagian thought, was quite popular in DeCaussade's time and place. However, I have some serious problems with the work as a whole.
Essentially, DeCaussade's emphasis on how one may only serve God in the circumstances in which one finds oneself is wise - and indeed, with the proper disposition, offering of any "present moment" can be a gift of grace. Those who are fond of the writings of Thérèse of Lisieux will see that this viewpoint has a marked resemblance to her "little way." Nonetheless, where Thérèse's means of expression, and consideration of her circumstances, give this approach an enduring realism and charm, DeCaussade's presentation seems quite close to both quietism (a passivity which, apart from theological deficiencies, often can lead one to a sense of helplessness and despair) and rationalism.
Since the work is a collection of letters and conference notes, many readers undoubtedly will find it as ponderous as did I. It becomes tiresome when the same, single point is made, again and again.
The quasi-quietism which I previously mentioned may be useful to those of a particular spiritual mindset, in which there is a primary emphasis on resignation in suffering. For those who, by contrast, are searching for some sense of hope in a "present moment" that is hellish, DeCaussade often seems lacking in compassion, sometimes to a point of bordering on cruelty. For example, his words of "comfort" to one who is suffering the grief of bereavement are that "God wants to be your only friend." It is solid to believe that divine providence can work in painful circumstances, but seeing these tragic times as inflicted by God (the passage I quoted can easily be taken as implying that a beloved friend died to accomplish God's purpose of one's being totally alone!) can lead one to run from, rather than embrace, faith.
I gave this book three stars because a few of its basic ideas are excellent: the importance of turning the will towards God, trust as essential to true faith, and not turning from today's chance for good in looking towards a future one cannot foresee. I certainly consider it a part of a well-rounded viewpoint of spirituality. But, for personal spiritual reading or use of ideas in pastoral application, I believe it has, at best, a limited appeal, and can be detrimental unless it is only one part of a far larger scope of knowledge.