This book will only be of interest to English speakers who are actively trying to learn German. It is really targeted to people at A2 or beginning B1 level. I tried reading it as a total beginner, and realized I did not have enough basic understanding to make any headway.
After completing a formal A2 German class, I had a much easier time of it!
One final note: the flow of language in book may seem awkward and repetitive at times. However, this is "not a bug, but a feature" as the author explicitly states he is doing this on purpose, in order to expose useful patterns and grammar points to the reader. Once I grasped that, I appreciated the book a LOT more!