I find that it has greatly improved my sense of direction. I live in an area where the roads are not always a grid (to put it lightly... having lots of lakes is fun for everyone but the civil engineers), and the GPS device has helped me correct my mental map of my area (which I am also relatively new to) several times now where I was off by as much as 30 or 60 degrees in what direction I thought I was going. (Between trees, clouds, and the fact that you probably shouldn't be staring at the sun while driving, if it weren't out-of-view most of the time anyhow, I find most conventional absolute cues to be useless.)
I suspect that rather than being an absolute problem, it has more to do with how you use it. Using it exclusively in turn-by-turn mode, such that it never displays any context beyond the next turn, is probably a bad idea. Using it zoomed out so it shows the surrounding half-mile or so (or more on highways) is what I find helpful. I never wanted to find alternate routes to things before because you just never know what on earth a road is going to do without a map (dead end? immediately shoot off in the wrong direction? who knows?), and the GPS unit is a map convenient enough to actually use. Even when I use it to travel to areas I've never been to, it helps me strongly orient myself and learn the 'lay of the land' in a way that simply driving once through an area, following your host to some specific place, really can't. It's like having psychic knowledge of the area you're in.
I suspect that rather than being an absolute problem, it has more to do with how you use it. Using it exclusively in turn-by-turn mode, such that it never displays any context beyond the next turn, is probably a bad idea. Using it zoomed out so it shows the surrounding half-mile or so (or more on highways) is what I find helpful. I never wanted to find alternate routes to things before because you just never know what on earth a road is going to do without a map (dead end? immediately shoot off in the wrong direction? who knows?), and the GPS unit is a map convenient enough to actually use. Even when I use it to travel to areas I've never been to, it helps me strongly orient myself and learn the 'lay of the land' in a way that simply driving once through an area, following your host to some specific place, really can't. It's like having psychic knowledge of the area you're in.