My dad once said to me, "You give a lot of books three stars." I do.
This novella prequel to Mr Penumbra's 24-Hour Bookstore is a good read if you've read the novel and have an hour to kill.
However, it's very dude-centric (there are some women, but they're mostly unnamed hippies) and didn't really add much to my experience or understanding of Mr Penumbra's 24-Hour Bookstore. I might change my mind after I've reread the novel though. We'll see.