I'll just echo recommendations for Sygic. My main concern when getting the phone was being sure I could get a strong GPS app that did not require any internet connection, and I've tried a bunch and Sygic wound up being the best by a longshot. The separate downloader is super simple and works great.
I came from 3 years on a Touch Pro 2 using iGO Nav-N-Go, and it worked great, but I haven't tried it on the S3 yet. I would guess it's excellent on Android as well, but I can't see the need for any other app after Sygic.