Lately there have been several stories in the national media regarding GPS units and how people are becoming so reliant on them it could lead them to harm. Do you remember the couple that was following their GPS to visit someone last winter and it routed them to the shortest route, which just so happened to be an isolated mountain road with no winter maintenance? Yes, they got stuck in the snow and barely survived.
That's just one of many stories I've heard how people simply look or listen to their GPS unit, and don't have a real clue where they are in the world.
How many people do you know that have those talking GPS units? Sure they are great in a crowded city, but as noted they can get you in real trouble when you're not paying attention and following a computerized voice instead of common sense on a rural country road.
I see GPS blindness all the time in the backcountry. Whether its friends or people I bump into in the woods, fewer and fewer actually have any idea where they really are at any given moment. They are simply following their GPS around. Last year I was with a hunter who I won't name, but after several hours of chasing elk I decided to test their knowledge on our location without using a GPS. Had I let them take us back to the trailhead we would have ended up in southern Montana instead of northern Wyoming. That person had no idea of the twists, turns, ascents and descents we had been taking and was instead relying on a waypoint for the return trip.
GPS units are great. I pack mine along with me on all backcountry trips, but I still use maps in conjunction with the electronic guide, and common sense.
As for those talking units, either as a stand alone or part of a smart phone, I get plenty of interaction and conversation with real people. I don't need a machine chattering at me as well.

Slow down and repeat that. You want me to turn left in 100 feet at the dead porcupine?