This is my first "new (ish) " car, also the first I am paying for entirely by myself. I have only had this car for a couple of days. I drove other A4s, and they have all been impressive, and none have exhibited any flaws. I have done very extensive research on these cars, and I am the king of preventive maintenance as evidenced by my very successful BMW ownership (next paragraph).
As much as I love my old BMW 318i (219,000 miles and still no problems), I have to say I am not terribly fond of the newer BMWs, and this A4 is actually closer in design and spirit to the older body style BMW, while being thoroughly modern with the latest toys.
My only disappointments so far are the lack of Bluetooth and satellite radio, but this is a used car, so being picky is impractical. Nonetheless, these things can be added to the brilliant factory stereo at very little cost. Also, I got this car for $22k, as opposed to $37k for a comparable new one. Audi also financed the car for me at 4.9%.
The Audi dealer I purchased from was surprisingly flexible and willing to match prices, VERY friendly people too. They even picked me up at home so that I would not be inconvenienced in juggling this car and my BMW when taking delivery. I feel lucky, as the other Audi dealers in my area have less-than-positive reputations.
The performance is more than ample from the turbo four, though I am still figuring out which mode works best for me with the Tiptronic transmission. It has "Drive, Sport, and Tiptronic" modes. I have found the paddle shifters useful, and I love how they respond no matter which mode you are in.
The seats are simply amazing, much better than the BMW seats, closer in design to those found in larger Mercedes. Mine has the heated front seats, adaptive xenon headlamps (auto-leveling and they swivel with the steering system), and the convenience package with rain-sensing wipers and other assorted goodies.
All in all, a very handsome and incredibly well put-together car with all of the right features, rich materials, and it looks/feels absolutely showroom new, even with 50,000 miles (really, it does, I looked at brand-new ones too).
I will post updates as the miles accrue.