This book first came out in 1978. The current edition has never been updated in thirty-five years.
Considering the advances in tools,glue,instruments,digital tuners etc. in this time, this book has now become a description of guitar repair frozen in time in the mid 70s.
It is perhaps obvious to say that anything that happened post '78 doesn't feature. The photographs are all black & white and so high-contrast as to be difficult to see what's going on.
The book also suffers because it's not project based - that being, if you want to achieve something, then there are no step-by-step instructions to achieve it.Guitar Player: Repair Guide
is the book that that superceded this one, and I would go to Dan Erlewine's book first and maybe look at this one second to see how poor it is.