There's a GPS system in our car. We've never had one before- just a small Garmin for geocaching.
I love that there is a map sitting right there all the time. I have zero sense of direction and I hate navigating by landmarks, and it's awfully hard to be reading a map when you're driving, so having a map sitting there is so cool. I still have my map in my head, but I can't memorize every street in northern VA.
I still use google maps to get anywhere new. The GPS in the car is definitely not reliable, but at least we discovered that on short, familiar trips. So we don't tell it where we're going and everyone is happy.
I'm really not a huge fan of the whole thing though. Sure, it'd be nice when you move as often as we do to have a device that takes you places, but I've also noticed that it's really easy to rely on them. There have been a lot of times when I've asked someone where a new place is (not even how to get there, just where it is), and they can't tell me because the GPS told them how to get there. I know it's just me, but one of the most important things to me when I move to a new place is to get oriented on a map so I know where I am. Driving off just following a GPS would drive me nuts.
But I still love the map, so I like having the thing in the car.