I don't use an onboard system but a Garmin Nuvi instead. It is OUTSTANDING! Whether or not you can enter a number is dependent on the software. If my Garmin doesn't recognize the street number he'll give me choices that let me get close.
I received my first map update free and now to update it is under $100. Not bad in my opinion. That's cheaper than the $10 per month VZnavigator charges and I don't need a cell tower. It is very fast and accurate. Navigation on the phone is very nice and handy but I don't think it quite compares to a full fledged GPS unit.