I'm updating this thread because I found it very useful to hear people's usage opinions when deciding which North America app to go with. I ended up with TomTom and used it recently in rental cars over about 1,000 miles around NJ/NY/PA and it was flawless. Big plusses for me compared to various nav systems in high end cars I have owned were the speed of calculating and recalculating routes, the quality of the routes and especially the clarity of the spoken instructions, including lane guidance. Most of the time, we found we didn't even need to look at the screen, just listen and follow the voice guidance. Also, the 4S GPS performed outstandingly well, bearing in mind it was not even mounted on the windscreen. It was just sat in one of the cupholders next to the gearshift the whole time, and didn't lose the signal once. The camera warnings and constant speed limit display were nice to have, but not essential. It really did the job.