As with most National Geographic books, you come to expect the best photographs taken over a vast period of time. This book certainly has those.
The full page glossy images are intertwined with great text about Yosemite.
The only thing that stops it getting 5 stars is that it is a relatively old text (1997).
Given the age of Yosemite this isn't a disaster, but it means some of the final chapter isn't perfectly up to date.