Personally, I just use one of the big three for iPhone which I already own. When driving, I'm not paying that much attention to the pixelated screen, instead the fools driving around me.
I bought it. It works for me as a backup nav (I have OEM nav in my cars already), for rentals, or otherwise. I just tried it once, and it worked fine. Some of the bad reviews are due to people with wifi only iPads trying to use it. You should j/b it, download a proper bluetooth stack and use a bluetooth gps, like a 5Hz Qstarz BT-Q890. People should be more responsible before reviewing, they give away 1 star just for spite or ignorance. On my 3G it worked fine. It's not polished yet, but as I said, it works.
Rip, Does is work well with only the GPS, not the 3G connection? I'm looking for one that is not dependent on 3G.
Well, it works well without 3G connection, since the maps are stored on the drive (1.78GB worth). Now it shouldn't work as well with the non 3G iPad, because that one does not have a proper GPS chip, AFAIK. A proper review of a Navigation software demands a bit more time. Maps are easy to get (Google, Navtec sells them for a dime a dozen), GPS signal is an iPad problem, ROUTING is what distinguishes a good Navigation software from a lousy one. I tested couple of days ago to find directions for my daughter's Summer camp, spot on with Toyota OEM NAV directions, so no complains for now. No crazy exits, 1/2 mile highway riding "because it's faster" etc. But I don't, and I won't use it everyday, so who knows? For $5.00 it's good enough for me, maybe the more expensive ones are better, but are they 10x better? I don't know.