I have just changed my Fiesta Titanium for a Mk 3 Focus Titanium X which has sat nav built in. It works, but isn't as friendly to use as the current touch screen type but is about as good as a 'stick on' type without the wiring. I generally use a gps to act as a memo to take me down a route have already created on the PC then transferred to the gps and loaded as a route.
Normally the rote is copied to the gps by USB lead or by removing the memory card and copying the files onto there but how can you do that with a built in system you cant connect to?