This is, not by any mean, a fun read. I couldn't call it "a book" either and I will attempt to re-read this multiple times to understand all the concepts introduced in this research.
"Structural Learning" has a lot to do with human cognitive process, how we obtain and expand knowledge, and how we use "rules" to build different frameworks for our learning: math, languages, communication, etc. by determining and analyzing the interactions between atomic elements of those frameworks.
It's near impossible to "review" this book in the sense of evaluating its writing or structure, however I will still give it a 4 star because it helped me greatly expand my knowledge of the process of learning and teaching.