More than a little nervous that iOS 6 maps is taking me to Idaho.
If you want to use your iPhone as a GPS, and don’t want to trust the maps, I highly recommend Motion X GPS Drive.
The app is $1. Voice navigation is $10/year (I think you can buy 30 days of it, but really? Ten bucks for a voice guided GPS is pretty good.)
I’ve been using that for awhile and really like it.
One final note: GPS takes a lot of battery power. If you don’t have a car charger, get one. Ideally something like this one which is just a USB plug for a car adapter. That way it will work with any USB powered device as long as you have a cable for it.