Perhaps some of the previous reviewers liked it because they use it for inspiration when designing at the very high visual level -- because really, this book is about pictures.
There is no useful information in the book about the design or construction of green roofs (except a couple of pages in passing).
Want to know more about how to design and construct using membranes, insulation, drainage, soil and gravel? Then look elsewhere.
Want to know more about how to design and construct a green roof on a new versus and existing building? Then look elsewhere.
How about planning the maintenance needed for a green roof whilst at the design and construction phase? Again look elsewhere.