I use mine as much off of the water as on. Its great when talking fishing with somebody and they are trying to tell you about a certain spot. Pull out the phone, and usually they are so impressed, they actually want to see if they can see the area they are trying to describe. I've used it to show family and friends places for them to try.
Have also used it to send a screen shot of exactly where I am on the lake or especially Red River, when having somebody meet up.
Data stays in phone memory, so cell service is not required to be able to access the maps, which is really nice in remote areas. Updates are free.
$9.99 divided by 2 years of use, well worth it in my opinion.
Trying to tell somebody exactly where you are, versus sending them a screen shot of a map of where you are, should an emergency come up, could be priceless.
"Hello, My name is Bill, and I'm a tackleholic"