Would you recommend your vehicle? I am thinking about buying a used, 2004 or 2005 A4 or S4... thoughts on repair costs? mileage? ups and downs of owning one?
Any input would be greatly appreciated.
(oh, I will definitely be getting the Quattro AWD, and the 1.8T or larger engine in mine!)

definatly a good car probably the most reliable German sedan and they have great driving dynamics. Quattro is great in the snow and rain and is very fun on ice. The handeling of these cars is so predictable its amazing. The 06 2.0T has almost no turbo lag i think it is a much better engine than the previous 1.8T.

repair costs can be high for Audi (only experiance with repairs is from a 97 A6 the A4 has been flawless so far and the first oil changes were negotiated into the purchase of the car) but unless you are willing to down grade considerably in the car quality most competitors repair costs are just as expensive.

Oh yes I would recommend either A4 3.2 or S4. I owned an A4 1.8T, then an A4 2.0T and since few months a S4 (all quattro of course). Best car to drive on wet or snow conditions; top quality of materials (even BMW is not close).