Im using the iPhone as a GPS with Apps from TomTom. The GPS software is the same as for their special TomTom for motorbike. The iPhone also works as a phone, and one press on the button to the left and you just say loud the name of who you like to call!
On the long motorway runs, I can listen to music from the iPhone, this also works integrated with the TomTom navigation system.
Need a hotel or camping, then Booking.com is right there.
When the GPS maps are not 100% - witch happens in some areas - then I use this special app, as seen on the photo. You just mark any point at google maps, and this will take you there - roads or no roads - doesnt matter. Very usefull.....