Please see our other backpacking gear comparisons as well.
Compare GPS devices at Hikeeer.com. A good GPS device can tell you where you are exactly on the map, which path you should take, and how much trip is there still left.
There are just basic functions found in all modern GPS devices. There are much more useful features on GPS devices, which makes the comparison a little harder. Use our GPS comparison to find the just device for your needs.