I found this book very good for two things: (1) if you want some of the history of the island and its different places, this has it; (2) it has very good pictures!
However, it is not a guide book, if what you want from that is clear and up to date information about places, transport, activities, etc. There are some very good websites that gave me the guide-book kind of info that this didn't, while this sat on the coffee-table for browsing afterwards.
So it's a perfectly OK book for reading and flicking through the pics, but it does not do what most of us want a guide book to do.