I use a Nokia Lumia 920 on AT&T. I have all of North America downloaded and when I am on a long days ride I turn Airplane mode on, turn on GPS and Blutooth and use a blutooth headset.
Nokia uses Navteq.
is their new mapping website that syncs places between your phone and computer.
I don't have any issues and it has always been accurate for what I have used it for.
I went on a 6 hour ride listening to music and enjoying photos and such and I used all of ~20% of my battery life.
Attached are some photos that I took with the Lumia as well.