Got my 3.5.1 and A4 update installed today, and my initial experience (limited to about 10 minutes worth of initial futzing at the dealer and a 15 minute drive home) matches what others have reported. I did four stop-and-restart cycles before I left the dealer and Bluetooth audio worked every time. Nav found and tracked my position straight away. No problems indexing my iPod. Tried a few voice commands and they all worked first time. It'll be a while before I get any more time with it though; I'm off on a business trip for the next few weeks.
Blue Candy Ti Hatch
Charcoal Leather 401A Parking Luxury Handling Nav