The book is a baaaaad sandwich —decent beginning and ending, but the middle, not so much.
The storytelling is poor, resembling a fabricated guided conversation based on FAQs. Paulo Coelho did recommend this book, but it's far from his standard... The conversation becomes annoyingly cheesy and unrealistic in the middle, with plenty of typical self-help tips thrown in there.
Apart from the middle sections, one aspect I found disagreeable is when the book discusses avoiding negative thoughts, even if it is through self-punishment.
First things first, one should not avoid negative thoughts but confront them. The right approach is to write down the problem along with its roots and solutions, and then the negative thought should fade from the mind all by itself. Should it resurface, reviewing the notes can help dispel them again. Psychology recommends facing the negative thoughts, not escapism. To the book's credit, it does touch on a similar concept by discussing the importance of facing your fears, but that contradicts the advice of avoiding negative thoughts virtually at all costs.
And that brings me to the second point which is the book's brevity, as it fails to elaborate on the nature of the thoughts labeled as negative by the author —that is assuming the best about his escapist method.
Lastly, most of the book lacks engaging stories. It starts strong with setting the plot and the garden, and it also leaves a good taste at the end with the story of Peter, but the middle is simply dry. It ceases to be a story and turns into a cooking recipe, similar to pretty much every other self-help book out there.