I meant "in addition to." As to your original question— Before I paid for a compass or GPS app, I'd explore the many free versions available. I've downloaded a few but haven't really used them enough to have an opinion...except I think they'll serve me just fine.
I search for apps thru the iTunes Store using my computer instead of my phone. It makes the process so much easier and efficient. Try search terms like "GPS," "compass" or "hiking." You'll find lots of things to play with.
Definitely get google earth.