Having read most of Coelho's books, this is, in spiritual content, not the most profound.
He mainly appears as a man driven by the material satisfactions of a spiritual quest, and hence the book tends to dwell on aims- the sword, and 'spiritual' exercises, which are actually mainly visualisation techniques used by people who are on an occult path. This may not be coincidence, since Coelho's background has been with the Occult and Magic.
These exercises whether literary props or not,have their deeper meaning treated quite superficially, and ones gets the impression that a few simple exercises will somehow help launch someone down a path of spiritual 'achievements'. He himself effortlessly performs these tasks conjuring his personal Daemon to be his temporal adviser and performs numerous other exercise with equal ease as he makes his way down the 'Jacobean' road. As with all of his books i think there are explicit spiritual lessons he is giving, of real value, but these are sometimes lost in the descriptions of New Age speak and concepts.
As a story it is a great read, the road story representing life and there are some fascinating moments. He does have a wonderful sense of the magical. Its a lovely book to read and I would well recommend it. I feel however that Coelho's deeper and more insightful works come in his later books, where he himself perhaps has matured spiritually and dropped some of the Spiritual egoism he has, which is often quite clear in this book through his attitude to his journey. The end of the story is profound and i think based on real revelation and this is a fine moment in the book of real worth to the reader.
I do think that this book, like quite a few of Coelho's works often escape serious scrutiny because of the sense of excitement he generates, e.g with The Alchemist, and this impedes useful criticism. It is not a coincidence on his Blog that he takes a very keen interest in obtaining serious commentary from his readership on numerous aspects of each book, from plot to style to character development.