We used to call "Pluggers" (early GPS units in the military) cocaine sticks. Because people would get addicted to them, and would lose their ability to read a map and navigate with a compass.
My preferred compass is my old Military Lensatic compass. I learned how to read maps and navigate with this, and it is still in my pack today. These are great units (kinda expensive though).
A great book on Land Nav, if you can find it is FM 21-26 Map Reading and Land Navigation (US Army). It is a basic level map reading and orienteering book that is invaluable!
Great post and Great info here!