We called OnStar over the weekend to get directions to a store we were looking for. OnStar then sent us the turn-by-turn directions with voice commands and directions displayed through out radio screen. This seemed to provide all the same information provided by the navigation system, except that it does not have the fancy screen and user interface. We didn't get the Nav system ourselves, but it seems like we get all we need with the turn-by-turn from OnStar. Am I missing something here (besides a fancy color screen)?