First 18,000 miles I've averaged 46mpg. About 80% motorway driving, at 70-80mph. If I drove smoothly everywhere, that would be over 50mpg.
Now that it's chipped, I aim to average 45mpg by the time I get to my destination - conservative driving to warm up the engine, blast it, then conservative again to get the mpg up (and give the engine/turbo time to warm down).
Some turbo lag up to about 1400 rpm, and you do have to watch it trying to pull away in second from a slow crawl - stalled a number of times, with the transmission going thud (not a pleasing sound - although norma for it to be that violent when stalling).
Tyre noise is quite bad. Wind noise is OK. Engine noise, for a diesel, is great so long as it's not idling. Very petrol like.
Also, get it chipped, because the transformation is unbelievable!
I've had no problems, other than having the rear wiper motor changed under warranty - Audi recall on the earlier (pre 2005?) models. No rattling that or squeaking this. Then again, I have so much crap in the car these days that I wouldn't know if it was the car of the brick-a-brac I carry around with me!
Handling is superb, although front end grip on acceleration, as you would expect with so much torque, can be tricky. With it chipped, I don't think the ESP can handle it properly, so the driver needs to be careful.
On the other hand, the steering is dead to this world. I've tried steering loosely with one hand to try and feel when the car is losing traction, but either I'm numb from the neck down or the steering is.
Oil consumption is reasonable at about a litre every 8000 miles.