Screen navs rock. They are easy to use and look good if you install them right.
Here are shots of the AVIC D3 in my '02 986S. I did the install myself. I have the BT cell phone adapter, the iPod cable, and the back-up camera installed.
The faceplate in the pics was my first try. I've since made a new one that's covered with stretched vinyl that looks completly factory.
The entire setup with all the extras and harness adapters was about $1100 from Crutchfield. The good thing is that when I sell the car I can pull it out and make it stock again in about an hour.