Not had many problems with the VAG DSG 'box's. They seem pretty reliable and shift better than most robotised units in other makes.

Do make sure that the oil and filter has been changed at the required 40k miles if you are buying an older model or one with some miles on it as failiue to do so WILL cause problems. Check the service history and if in doubt, ring the dealer / garage who has looked after it for confirmation.

Apart from some electrical niggles, the A3 is pretty good. Only downside of the petrol V6 Quattro is the MPG figure..... I'd much prefer a 3.0 V6 TDI engined one any day, but each to their own.