I love this book, but it's not the 5 star read it could be.
Roughy half the book is a collection of essays by various authors (Neil Gaiman, George R.R. Martin, etc) and essays written by Cassidy himself, each focusing on a different library from around the USA. These essays are excellent; some of them dramatically moving (The Little Library That Tried), and even the ones that are just so-so are very interesting.
The other half of the book is a collection of photos Cassidy took of librarians during the ALA conventions of 2014, 15 and 16, each with a caption underneath quoting the librarian. These photos are also very cool and I really enjoyed seeing the diversity of faces. But the captions could have been SO much better. You don't notice it for the first few pages, but after a while, the sameness of what they're all saying starts to take on a tone of defensiveness and justification. A better editor or maybe just a better plan at the start, could have thoughtfully cultivated a collection of anecdotes that better expressed all the myriad ways librarians are indispensable, without sounding like they were trying to avoid the axe.
Still, overall, a very excellent book and I'm really, really pleased I took a chance on it.