Several readers have urged me to try the Gokivo Navigator for the iPhone [iTunes link], so today is the day. The app is U.S. $4.99, but that only provides you with GPS navigation for 30 days. After that, the app costs $4.99 monthly or you can purchase a year of service for $39.99. That's quite a bit less that the AT&T nav solution [iTunes link], and makes the Gokivo app quite competitive. The app includes a Traffic Tracking Center, text to speech so street names are announced as you drive, and it has iPod controls so you don't have to leave the app to change your music.
Like the AT&T app, if you are out of range of the data network, you won't get maps. And like most of the competition, Gokivo gives you an estimated time of arrival, distance to your destination, and your current speed.
The map doesn't work in landscape view, which I consider a strong negative. It's easy to navigate to your addresses in your Contacts app, and the feature is nicely integrated.