I wouldn't dream of not using a
GPS- it's become second nature. When I was in the field for work I used it, and now volunteering down here its critical for collecting data. I find it awfully reasurring (the most common thing I use it for while hiking for fun is to mark where I left the car *just in case*). I use a Garmin Etrex.
However, while its hard to imagine life without it, I always carry a map and a compass as backup. those batteries tend to drain quickly.