Hey I found a good Navi system. I am running iPhone 4, But it still works for the 4S... Go to the app store search GPS by TeleNav. I just installed it, its free and it works great!! Check it out!
i actually call sprint cSevice
and she said that sprint nav is not supported in d iphone. but wen i click my account and services that they offer for my phone4s it's says
"This service works with your phone."
she direct me to use d maps, oh well she thinks i dont know how to use my apple phone, so i keep asking and she told me to go to app store 'that it'll be teleNav and that she's using that teleNav, again i didnt get it' it's not even a SPRINT app or services
See this thread for an explanation which answer your questions and concerns, and pretty much hacks this subject to death:
In a couple months Apple will be supplying their own mapping/navigation software within iOS 6: