I specifically want the on-board map data. Now that data usage is under quota (again!) I don't want to waste it on mapping. I have been testing the capabilities with Google Maps though.
Apple Maps, IMO, suck. I have tried it and well over half the location data is flat out wrong in my region, with some businesses being marked as far as a mile away from their actual locations. It's so bad, I gave up on submitting corrections and switched back to Google Maps. Now, if Apple were to pay for map corrections....
Also, I am often enough traveling in areas where there simply is no cellular reception, so that's a deal-killer right there.