[maaku]

Once you trust the machine to get you back, you can retake those brain cycles previously used to track that information to do something more productive, e.g. think about what you're going to do at the destination, engage in social banter, or plan the rest of your day.

You don't realize it, but you're actually less productive than your friends with GPS.

[colanderman]

Not only do you use a different part of your brain for navigation from most everything else, it grows to accommodate its use: http://en.wikipedia.org/wiki/Hippocampus#Role_in_spatial_mem...

I never use a GPS, and generally never have to spend time thinking about directions. They just come to me, and eventually I'm at my destination and wonder how I got there. Compare to futzing with the terrible UI of most GPSes and interrupting conversations to listen to them tell me how far until the next slight bend in the road.