I have had Detour on my phone for at least 18 months. Havent found the time to open it until last weekend. I am FURIOUS with myself for not doing it sooner. It was a fantastic experience! My teenage daughter and I did the "Cool Gray City" tour of SF and we were blown away. It was fun, immersive, and highly informative. My daughter is asking me to do another one this weekend.
The coolest thing about the app is the sync feature -- you and your friends can listen to the tour and pause and restart -- and all of you stay in perfect sync. Its a simple thing but it allows you to experience the little surprises together, which is fun.
Highly recommended.
Rickover about Detour - Immersive Audio Tours