Hello,
I am a psychologist and "practicing" ACT for several years.
I have several books on the ACT including this one, which is therefore in terms of pages.
I was eager to find out, from the book by Harris RUSS it promised more interesting.
The reading was tedious, information abound but unfortunately not always with great success, but they have the merit to be present.
Details of underlying theories are a complicated extension. Indeed, they appear on reading winding and very precise, sometimes bogging in lighting that darken each other. The French used is not always with great accuracy, and the sentences are quite heavy. This would not pose much of a problem for a book of reasonable thickness but heavy enough in this case.
On my supervision, I would never recommend this book to discover and deepen the ACT and for the reasons mentioned above.
I must admit that I am disappointed.