How I Use It
I use this personally when I travel to new places. I am always surprised by some of the historical locations that pop up right where I am standing that I had not known about before. I was in DC and discovered I was standing in the location of the Reagan assassination attempt - which was not marked otherwise. I wrote a blog post about it : http://speakingofhistory.blogspot.com/2013/05/field-trip-app-discover-history-all.html I really like this app.
I have not used this app with students in class but have encouraged my students to load it on their phone and use it as they travel. There are some possible curriculum ties with local history but have found it most impactful when I am traveling in a city that I am not as familiar with historically.