Definitely entertaining, but it didn't have much merit for me beyond that. 
 Was pleasantly surprised when I started the audio book and heard Kathleen Wilhoite (who played Liz Dane on Gilmore Girls) narrating (I always forget to look at the audiobook narrator's name before I start the book). She has a very distinctive voice, which worked well for the main character, a girl in her early teens, but she could class it up nicely for Bernadette's voice. She also handled several different accents and tones of voice well, which surprised me. 
 Would probably make a good book club selection. I think fans of Mr. Penumbra's 24 Hour Bookstore would enjoy this. Both titles involve a quest/mystery that involves research and travel to solve, and both are written in a conversational type of narrative. Where'd You Go Bernadette is about half epistolary, though, which is a major difference between the two.