Surprisingly the BT audio sounds much better than even CD's in my car. I'm pretty amazed and it is one of the features that makes me so happy I decided to go with the CT. I have the premium audio package and it sounds really good for a stock system.
Also, the BT audio connects back up the minute I jump into the car and plays exactly where it left off.
Best sound quality is the CD, second is Iphone with aux cable, next is bluetooth (a definite loss in low end frequency), and FM SAT are surprisingly poor, with AM the worst (as one would expect). I was most surprised how poorly the quality of the SAT was, I was expecting more. Pandora through the Iphone with aux connection is vastly superior to SAT