Hi I've fitted the new RNS 510 from VW. It was very easy to fit, and gives the full functionality without having to mess around with Vag-com or anything. It took me about 30mins from start to finish.
Also sounds much better than the standard RCD300. Not sure about the sat-nav voice though, she sounds very stern

You get a 30Gb hard disk to copy all of your MP3 files onto, it plays DVD's and accepts SD cards through a front slot. Finally you get to keep that OEM look at it comes direct from VW.
Hope this helps,
Nigel