The navigation apps are all quite terrible. This weekend, in NY, my wife and I were using Google Maps on an Iphone 5S and it was terrible! Took us in totally out of the way places. As soon as we got back in my car with my Garmin, all was well.
I've had more GPS units from Magellan (He got lost in the Pacific and died. Never did make it home. Why name a GPS after him!), Tom Tom, etc....None can compare to Garmin. I just bought the 760RV...Fantastic! Will keep an RV out of trouble....low bridges, weight restrictions, no LP tunnels, etc....