Hi - I've got the Seat factory fit satnav, it's a lifesaver for me really, I do many miles on business and nevery get lost anymore, it's good for routing out of jams, calculating how far you have left to travel and estimated time of arrival. The sound of the stereo comes from the unit too, seems better than the standard HU, plus makes the dash not look so sparce. It is an expensive option, so don't just buy it cos it looks good, well not unless you have cash to burn!!!!
I've uploaded a pic of mine so you can see what it looks like....