Have the TomTom app, uses it all the time. Brilliant.
Don't need to buy the TomTom cradle, but a car charger (any one that works) and a cradle makes it much easier to use.
In particular, I like:
- Free map updates
- Advance South African voice that reads out the street names (even though she can't pronounce Johannesburg)
- Offline data
- Can be shared between multiple iPhones/iPad (allthough the traffic service can't)
- Can be used with the traffic service, including on a month-to-month basis if you for example know that you will travel quite a bit during that month. Although Google Maps now has free traffic, so I doubt that I will use it again.
Garmin GPS has been in my closet for months!