Why? 1. Doesnt use data. 2. Accurately monitors speed and distance traveled in mph or kph!!!! -> :) 3. Free 4. Customizable settings- you can make it say your stats at customizable intervals. This is a great app. It seemed a little sketchy at first, but all in all one that I would even recommend to be featured by Apple. It took me forever to find a good app for monitoring my speed and top speed skiing and this is perfect. We tested it out on the highway, going 100kph.