Other than the random "Turn around, your heading the wrong way...*10 seconds later* Turn around, Wrong way retard", this thing is an animal.
It usually happens in construction zones on the interstate, and when I'm hungry. My GPS knows I like taco bell, so it'll turn me around on an exit with a Taco bell. It's happened numerous times now when traveling.
Haven't tried it off the beaten path yet, but I haven't updated it since I got it 2 years ago, and its pretty good with back country roads.
The battery life... About 5 hours, with the brightness on 10%. I always keep it low, I only use it at night.
It's very adjustable. Change the voices around, download new ones, change the map view, rotate the map view, plan a route, use it as a walking gps, avoid certain things like tollroads, freeways, hummers
Plans by Shortest time, shortest distance, or quickest drive. Which, for the life of me I can't figure out. I guess it's a combination of the two.