The sat nav in the 4200 I find actually okay.
Used it over the weekend on a couple of hours journey and she spoke when needed, and got us to the door of the hotel.
Yes could have used the sat nav on several phones and the iPad we had with us, but no cables, suction cups, or balancing acts where needed using the 4200 one.
I do find the copy discs I use to have limited life though. I think being CD-R's the laser can have trouble reading them.