I recently bought a Nikon D810 as a christmas present for my wife. When I bought it, it was part of a package that included the body, a battery and charger, a memory card, a bag, and a GPS Unit. All for the price of the the body by itself.
The one thing that I'm curious about is, what is the general purpose of the GPS unit? Is it just to record metadata on the image so you know where the photo was taken, like if you took a picture of a waterfall or something? Or can one use the camera GPS for other things?
Normally I would just ask my wife this, but as it's a christmas present, I don't want to bring it up.