A review of the AT&T Navigator app for the iPhone 3G and 3GS. This is a turn by turn GPS navigation service, where the app is free and AT&T charges you $9.99 a month. The app works as advertised with few frills and a couple issues. The biggest advantage of the subscription service is there are no big maps to download and keep on your phone, you always have current maps, and can subscribe only when needed.