"Kicks Apple's Maps butt"5.0 starson by Colper8
Pros: -Great interface.
-Extremely quick voice guided response time.
-More accurate than any other iOS "maps" app.
-Re-routing is a breeze.
-Voice guided for iPhone 4. Apple doesn't allow this with theirs.
Cons: Low on features (check-in and social stuff like that). But this is probably due to Apple restricting them.
Summary: The best option out there for iOS voice guided GPS, hands down. I mean, it says something when Apple hires Google Map developers to make theirs better. Google won this fight.