We have tried many GSP solutions and this is the best. Installation file is pretty big, for example a full Europe package is ~1600 GB. Use a good speed wireless to get it.
After you are installing it (it works both on iPhone and iPad 2+) you are asking to make basic setup. Please note that this application is very intuitive and easy to use.
To test it properly start it in the car or outside (in buildings there is not GPS signal). It using only GPS signal (you don't need mobile signal).
In Shop section there are many free packages to upgrade with new voices and other. Paying a fee will allow you to use points of interests add-ons.
This is a great application and i recommend to spend money on it.