I have the book but thought this would be more convenient and as the book is so good thought the app would be worth the price. However, they're are none of the great photos included in the book to show you what you could be looking for, just a space for you to upload your own. The information on each location is a bit clunky and just generally a poor relation to what is a great book!
Already have the book but purchased app thinking it would be convenient to you information when travelling. The app is slow and crashes when you try and zoom in on the overview map. stick with the book. It has more locations in. Disappointing considering the not inexpensive cost of the app!