After playing with it I see it's missing some of the software features of the hardware GPS units. One that's a nice feature for a navigational GPS is the help feature which shows you the address of where you are and the closest hospitals, police, pharmacies, service, etc.
I tried a few addresses and in the simulation mode I found it amusing that it drove faster than the speed limits for the roads it used. It's consistent about it too. If I leave and go back into the route fresh the simulator always drives faster than posted speed limits and you get the warning repeatedly. It also failed to follow its own designated route several times requiring recalculations.
The display doesn't allow for gesture zoom and pan. Touching the display while on a route changes it from 3D to 2D view. It appears that you can only change the view zoom in 2D. The 3D view is a bit cluttered and I'd prefer to be able to zoom in a bit farther to reduce the amount of POI icons on the screen.
It does use the iPhone contacts list from the phone. I thought it had been previously reported that it didn't.