Using Navigon MobileNavigator (North America) for iPhone more because it has slightly better iPod controls than TomTom U.S.A for iPhone. It allows awkward playlist selection and displays current song info while TomTom only implemented Back, Play/Pause, and Next buttons. Navigon attenuates a song when providing voice directions while TomTom pauses playback. Navigon's approach is better when there are back-to-back audio cues. Both apps should simply provide a user preference to attenuate or pause for instructions.
Navigon has a more pleasant text-to-speech voice. It pronounces "San Francisco" well, and it's funny every time it says "Kalifornia" like our Governator. TomTom is totally missing out by not making their voice packs available to iPhone users via in-app purchase. D'oh!
Navigon's maps look cooler than TomTom's at the expense of easily legible street names. However, Navigon's lane guidance is more detailed than TomTom's, and has a version designed for night mode. Navigon uses the iPhone's ambient light sensor to automatically switch between day and night mode whereas TomTom annoyingly requires manual selection.
Navigon also beats TomTom in the area of overall stability. TomTom has failed to launch on a couple of occasions, and has crashed when it can't parse an address in a contact. Navigon failed the other day on a seemingly easy address, but at least it said it couldn't parse it instead of crashing. TomTom got lost navigating from 4th and Mission to the Bay Bridge during a test. It was docked in the TomTom car kit so it seems like it should have had a strong GPS signal among the tall buildings, but didn't check the exact satellite locks. Navigon got lost once after deviating from its inefficient (speed-wise) route. Both apps occasionally lose track of North when stationary (e.g. at a stop light) although have yet to test a theory that both apps seem more optimized for portrait instead of landscape iPhone orientation.
Unlike TomTom, traffic and road hazards on the Navigon are supposedly augmented with anonymous data from other Navigon users. Both apps could do a better job of presenting traffic conditions on the map, especially compared to the old Dash nav system that also used info from other Dash drivers. At least Navigon's data seems more copious and up-to-date. TomTom does have a turn-by-turn overview of a route, which will hopefully be added by Navigon too.
Overall, Navigon edges out TomTom on the iPhone. The decision is slightly harder since TomTom is on sale for half the cost of Navigon (whose traffic info is an additional in-app purchase) through December 28th. It remains to be seen how expensive map updates will cost. Really wish Dash would release an iPhone app, but the chances are remote now that RIM owns them. Almost bought Magellan's new iPhone app, but reviews claim that its iPod controls are bare bones like TomTom. On the plus side, it looks like Magellan is using their own keyboard interface for easier typing while multitasking.
Anyone who is pragmatic will realize that one can buy a dedicated nav system for the same price as TomTom or Navigon plus the TomTom car kit. Using the iPhone means the apps have access to its contacts and music. The car kit's Bluetooth speaker phone is nice for those who need one, and it's occasionally handy to have real-time turn-by-turn navigation on the iPhone as a passenger. Most importantly, the iPhone always leaves the car so it can't be stolen.
It'll be interesting to see if Apple includes their own nav app a la Android 2.0 with the next iteration of the iPhone since they bought a cartography company a few months ago...
