If there is one thing that I am learning, now that I moved semi-permanently back to my home town: many of what I considered pretty established technology is a very urban thing.1
Just an example: I use a couple of apps on my iPhone that use the geofence feature in some way or another. For the sake of a simple example, let's think about geo-based reminders. So I might have set a “Buy pepper” reminder for my next trip to the grocery store.
Apparently the iPhone uses cell towers and WiFi for the background location – which is probably a lot more energy efficient than using GPS. This works great in dense areas like a town; in Düsseldorf I was able to set a geofence and could be sure it would trigger around the same area, give or take a meter or two. It does not work so well in a more rural area2 like where I live now. The density of cell towers and wireless networks is just so, so low. There are not many WiFi networks that the phone can use to locate itself and once it's only the cell towers, all bets are off: there are not many of those, either.
The precision at this point drops to about 500 meters. Given that I already live on the outskirts of the town, my current work place is a bit closer to town and the supermarket is right at the corner of the city center and all three of those points are roughly 500 meters apart, you can see how this precision might be a problem. I don't need to be reminded to buy pepper when I get to work.
But maybe everything will be better once the supermarket here deploys iBeacon?