There's an app called Rocket Track out there too, I have not personally tried it, but some people I know that have like it better than GPSRL.
Well, the LCD-GPS Module in the LCD receiver gives you the distance and the arrow/heading to get to your rocket, that's basically what you'd get with an app. And it doesn't require another device so it doesn't matter what's in your pocket. The problem with an app is that there are more pieces to maintain, and invariably if you have an app that talks to hardware there are going to be incompatibility issues at some point in the natural upgrade process. With everything in one box, all those issues go away.