I had both the book and the app and they coincided pretty well, but if taking only one, I'd probably opt for the book because it's easier and faster to scan the listings when they're all on one page. On the other hand, if you have GPS on your phone, the app can save you from getting lost or wandering around searching for your accommodation because it shows you exactly where you are in relation to the GR65 and/or the gite you're heading for. One caveat: The app map didn't always locate things accurately. Using the app map and GPS, I once ended up at a retirement home instead of the municipal gite. Another time, I arrived at a farmhouse surrounded by barking dogs and was informed that the gite I was looking for was a kilometer away, back in the town I had just left!