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.
I found the map to be a bit jumpy as my car moved along, rather than a smooth real-time display. While my home address was easily found (not the case with all the nav apps I've tried), a lot of POI information is missing or out of date. That's a bit surprising, because all the data comes over the air, rather than being pre-loaded to the iPhone memory. Some theaters that opened up near me a year ago aren't listed at all, which is a bit surprising.
The on-screen display is useful, but not what I would call graphically striking. Of all the navigation apps I've tested, I think the Navigon app still has the best looking display.
The whole world of iPhone nav apps may change if Apple approves the new Google turn by turn app for the iPhone. It will be free, and is currently included with the new Verizon Droid.
If I were thinking of buying something, perhaps for those holiday trips, I'd suggest holding out to see what happens with the Google offering.
If you have to get something now, the Gokivo app is reasonable, mostly full featured, and reliable. Of course, you'll have to live with the points of interest data being a bit thin, as well as the lack of landscape view.
As the holidays approach, I'll have a complete survey of the iPhone nav scene, with some recommendations for those who haven't already taken the plunge.