This book hit high and low points for me. Once I finished I was kind of confused about whether or not I actually liked it. I'm going to say no. If I have to think hard about whether or not I liked a book I probably didn't like it.
The best part of this book, indeed the best part about working in a library, is the patrons. Like any library staff member worth his or her salt, Douglas remembers the crazy, funny, and dumb patrons and tells their stories in an amusing way. The chapters that consist of play-by-plays of crazy days in the library and one incoherent rambler after another are the best. They made me giggle and wince in sympathy.
On the other hand, the book suffers from the same problems as a lot of tell-all novels. With the good, interesting, universally fun stuff, you get the boring stuff, the "you had to be there" stuff. In Douglas' book this takes the form of his entire chapters devoted to his crazy coworkers. The thing is, everybody has crazy coworkers, but most people don't obsess over them, or concern themselves with their actions enough to put them down in a book. There's also the fact that he's combined incidents, escalated the humor value and changed the coworkers' names and job responsibilities to the point where it's like he's basically made up random stuff about the people he worked with, and that's even less interesting.
I was also kind of bothered by the fact that nobody ever helped him out. He was threatened with bodily harm several times in the book and not once did he get a coworker to take it seriously. It's a completely different environment than I'm used to and the indifference bothered me. That's not his fault, though, unless he embellished it for the humor value.
The book also needed a good editor. There were a lot of spelling mistakes, like "ally" for "alley" something like five times in two pages, which should have been caught before publication.
I do really enjoy the author's "Dispatches from a Public Librarian" at McSweeney's: http://mcsweeneys.net/links/librarian/ He seems better suited to that format than books.