This is a fairly short book which discusses all the studio Ghibli films (well from Laputa: Castle in the Sky to Ponyo on the Cliff by the Sea) plus less emphasized discussions about the Pre-Ghibl days and few sentences about non-filmaking work.
The discussions are pretty basic, brief plot outlines, some personal details about Miyazaki and Takahata, and a bit of summarizing of the social contexts in which the films were made. Much of this is a case of stating the obvious and the sort of snippets you could pick up from television interviews and/or other peoples works. Many of the films (particularly the Miyazaki films IMO) could do with much longer treatise, however I guess that is not really the point of the book, which seems to be an introduction to the films.
This it does well. There is not too much worthiness in the text, each of the works is concisely discussed in chronological order allowing the development of themes, which are often revisited across a number of films. The simple and gentle style of the authors complements the material of the films and although you are left 'wanting to know more' about each of the animations you have not already seen, I was glad it didn't go into too much detail as this could detract from watching the unseen films. For those films already seen, there was nothing really new.
Not really for avid Ghibli fans then, but good if you have seen 'Spirited Away' or 'Princess Mononoke' and want a bit of a pointer to other works.