I had previously attempted Kempis' "The Imitation Of Christ", and found that it was difficult to disassociate from the intended audience of that book (cloistered religious). I'll try to review it in the near future. In any case, my experience with Thomas a Kempis made me a little gun-shy with regard to spiritual primers intended for religious communities. One of the challenges of "Self-abandonment" is the extent of its direct communication between the author (as spiritual director) and the nuns with whom he communicates. Nevertheless, the more generalized introductory sections overcome this difficulty.
I happened to be in the midst of "Self-abandonment" at the time of my grandmother's death. I must say that in retrospect I could not have found a better companion for those days. de Caussade does an excellent job at communicating the spiritual benefits of acceptance, duty, and forgiveness. It ought to be the goal of every Christian to make each day, and each moment of each day a paean to the Lord - seeing His will in all things - even small things and most particularly in painful things is a crucial step toward living a truly Christian life.
Finally, I don't know whether to call this book "life changing," as I believe that one must already be at a certain level of acceptance prior to realizing benefits from the approach that de Caussade recommends. Nonetheless, it is a useful and helpful aid to the continuing trauma of living in the world but not of the world.