I have the 2005 Cayenne S with 19" wheels. The odometer is about to turn 47,000 miles. I love my Cayenne. It has a few quirks that the the 2nd generation cayenne has addressed such as touchy brakes, Super stiff rear suspension. I have had a few service items that the dealer has address. The best part of owning this car is driving this car. It is a fun car to drive period. The car handles and corners great. The engine sounds cool too. It actually drives like a Porsche. I own a 997 2S. If you like to drive, you need the S, GTS or Turbo version. The 6 cylinder is too underpowered for the car's weight.
Since you sit up higher than cars you can see well in traffic and on the highway. The all wheel drive makes the car corner very well for it's size. It sounds cool too.
Most have been addressed in the 08 and 09 2nd generation Cayenne. Rear suspension too stiff, brakes are touch. Front clip needs to be lowered a touch.