You may be shocked, but no, every librarian has not read every book in the library. That being said, I just read this book for the first time. Typically, I don't think of myself as much of a science fiction reader. It's a genre that struggles to hook me. That's why this book works; the absolute absurdity of the events pulled me in.
Having waited thirty years since the original publication, I frequently found myself laughing over the gadgets that are now a commonplace part of life which were truly fictitious in 1980. The double talk, twists, turns and silliness are such a realistic part of the characters' lives that the reader almost feels bad laughing, almost.
If you've never read it, all I can say is, "You've never had a day as bad as Arthur Dent's. You've also never had quite the level of excitement."