Very close to half of this book is about the making of "Raiders of the Lost Ark", and if it was released as just that this would easily be a 5 star review. The book goes behind-the-scenes through the production of each film from conception through to the nervously-awaited first weeks box office takings. While it mostly follows Steven Spielberg's point of view, absolutely all aspects of the productions are explored, cast and crews quoted.

While this is true for each film, as I said Raider is half the book - the page count for each film drops by orders of magnitude, as I suppose for some reason less documents and documentary footage exists for the subsequent films?

Temple of Doom still has excellent coverage, but while Last Crusade is full of interesting information the difference between it's coverage and Raiders is very obvious - in one sentence 8 days shooting is skipped over, including the entirety of the sequence set at sea which couldn't have been an unremarkable shoot.

Crystal Skull suffers particularly - not only is the page count comparatively miniscule, but much of what there is reads like press-releade material. 

The coverage for Raiders and to a lesser degree Temple is so good that overall this is still a magnificent piece of work which I thoroughly enjoyed pouring over, easily amongst the best of it's kind. I can only hope for an expanded edition one day!

UPDATE: the author was a guest on the excellent "Indiana Jones Minute" podcast and explained he wanted to make 4 books, one for each film. The publisher insisted he rolled it into one, giving him less time (and money) to research all the films as thoroughly as each other. Source: The Indiana Jones Minute Season 3: Minute 75 of The Last Crusade "Just when you were becoming interesting". Which explains it, but still disappointing!