I went in yesterday to have the dealership look at my radio. Since I bought the car in June, the radio has randomly displayed "LOCK" and not let anything work. I always had to restart the car to get it to go away. Yesterday morning, for the first time, it displayed "ERR" and wouldn't let me eject or play the CD that was in it. It would play the radio though. The service tech told me that he had reprogrammed the radio with a newer program per some service bulletin GM had out. I didn't know you could do that. Hopefully that problem is solved once and for all. I had thought of going aftermarket, but I like the stock look.
Problem #2 - The brake light likes to flash every so often, but that looks like a fairly common problem so I'm not all that concerned about it. I figure GM installed faulty switches.
Problem #3 - The door pulls have warped slightly, but enough that you can see the edge of the upholstry underneath them. Why they didn't cut it a little extra longer and fold it under into the hole, I'll never know. Not very noticeable unless you're looking for it.
Problem #4 - I get a lot of wind noise from the upper back side of the driver's window. It starts at about 35mph. It never increases in volume with speed and the radio is always up, so it never really bothers me. There are times, however, that I like to drive around with the radio off and the last thing I want to hear is a leak by my ear.

The car's got almost 11,000 miles on it. Other than the above mentioned items, I'm very happy with this purchase. 30mpg around town, 35 on the highway, one tank a week...