With TomTom for iOS you never have to worry about outdated maps, ever. TomTom updates maps automatically, free of charge. It works like this: You get a notification that a map update is available, and then you can download it over a 3G/4G cellular connection--say in your car, just before driving. This is a huge deal for a storage-based GPS app.
Another plus: the iOS app uses TomTom's IQ Routes technology to recommend the fastest route. In the U.S. and Canada, IQ Routes estimates travel time based on actual anonymous user travel times collected not only for the route, but time of day and day of the week. This gives you a more accurate travel time because things like rush hour, pedestrian crosswalks, and traffic lights are factored in along with the speed limit. If you want to up your game even further, IQ Routes works in conjunction with TomTom HD Traffic, a $19.99 annual subscription service you can buy in-app. HD Traffic delivers live and comprehensive traffic information every two minutes.
Navigating with TomTom for iOS was a stress-free experience. Advanced Lane Guidance, another feature for U.S. and Canada driving, tells you which lane you should be in when approaching a tricky juncture. I've not missed an exit or interstate transition yet, thanks to this system with its pulsing green arrows and photorealistic images. I also liked how the software displayed my actual speed vs. the speed limit--e.g. 50/45 mph--in a corner of the screen.
At $59.99, not including $19.99 for a year of HD Traffic, TomTom for iOS is one of the most expensive navigation apps here, but it's a really great choice. It works not only with the iPhone's internal GPS receiver but with most external receivers as well.