I've been using it for a while now, both to determine which peaks are in some of my pictures and to find out where exactly I was when I took them.
Today, I spent a long time figuring out some of the distant peaks on this picture:
I learned that the hardest trick is to find the location (and in this case I had to adjust the altitude that Google maps thinks belongs to that location) and the direction, using trial and error, generating lots of pano's. That can take a while indeed, but with the results it delivers, I can live with that! Fortunately, after that it's easy. Just make the size of the photo match that of the generated panorama and look real close.
I'm the one that disapproved your post because I thought the app you mentioned was not free. If it is, I apologize, if you post it again I'll approve it this time. Just mention that it's a free app to avoid confusion (and to make sure other moderators don't think it's commercial and disapprove your post again).