About 2 months into owning the car, the 6-disk CD player stopped playing CD's and would not eject them either. I brought it to Mazda service and since it was under warranty, it was replaced that day within 2 hours. The Service center was very good.
Also one time after an oil change, the check engine light came on, so I brought it back and they took care of it right away. The computer just needed to be reset. Other than that, nothing has gone wrong with this car.
Very great, smooth driving car. Quick and super reliable. I would recommend this car to anyone. I owned a Jeep before the Mazda6, so when I switched to the 6, at first I hated that it was so smooth and comfortable and pleasant to drive. I was used to being the bumpy, uncomfortable ride of the Cherokee. After about a month, I realized that smooth and comfortable is much better and now I would never think of getting rid of this car.
I too had problems with my Mazda6 6 Stack CD changed. This occurred during the first month of owning the car (Sept 2002) where it just stopped ejecting CDs altogether. Once the replacement arrived (4 weeks later!) it too had a quality issue. The replacement played OK, but occasionally would skip through tracks. This was quite annoying as it was hard to diagnose and prove to the dealer, who had to sit in the car listening for 15minutes. They then replaced that unit also. The good thing was the replacement unit must have been internally different as it now plays CDRs and CDRW where the original didn't. Other than that, this car is absolutely fantastic.