I have a Garmin unit mounted on my car windshield that comes on with the ignition, and the user experience is just so much better. The route lines don't blend in with the background and it has large labels that are actually readable. The low angle of the 3D map actually lines up with the view through the windshield, which compresses a decent amount of roads into a small space. Even the spoken directions are better (I've used British English Daniel for years, and I rarely notice when someone speaks in a British accent).
I don't often set a route, so it mostly functions as an always-present map, which it does exceptionally well. I especially like the banner at the bottom that shows the road I'm currently driving on and the banner across the top that shows the next cross street.