I have 3 of them. I use them for hunting in CO. I went on a week long pack in pack out Elk hunting trip. Had a $900 one and ended up using my $160 Magellan most of the time. I always had a back up. It's good to know how to "really" use a map and compass to plot you location and where you are. Most people don't really know how to do this and rely to much on GPS. I took a week course on it and still have problems sometimes.
I have my pilots license and I use my hand held all the time. The planes I rent don't usually have GPS unless you shell out the big bucks. I fly a 152 most of the time, just to take chix up and short trips for dinner, and always enter the long/lat of the airport which I'm landing in and it gives me ETA (estimated time of arrival) and distance to the airport, average speed, all kinds of shit. I really don't have to use them anymore, but I always keep one in the plane to be safe.