I cannot recall anything major going wrong mechanically (knock on wood).
I suppose my biggest peeve can't actually be considered major, because it is purely cosmetic. The trim package around the bottom of the vehicle continually comes loose from the body of the vehicle, which detracts from the aesthetics.
Also, the front end trim - which I had replaced once under warranty - continually bottoms out leaving an ugly scrape right at the 'nose' of the vehicle. The new trim was redesigned (I guess they had to replace a lot of them), but even the new one hits the pavement a lot. Oh well. What do you expect? You want a sleek sporty look... you pay the price.
Finally, my leather interior is becoming worn - especially the driver's seat (again aesthetics).
I've heard some complaints from fellow Camaro owners about T-roof leaks, but thus far I've had no problems.
In fact, the only problem that I have with water penetration is the rear hatch. I can't park facing down on a hill when it's raining. There are channels that were designed to allow the water to run off, but they only work if gravity allows them to. If the car is facing downhill, the water in the channels doesn't run off, it spills over the side... into the vehicle. I suppose I should have listed this in the faults above, but the solution is easy - just don't park facing downhill!
Overall, I'm quite pleased with the vehicle. Even five years down the road, it still turns heads! I consider this an early sign that this vehicle is destined to be a classic - especially since the Camaro is being discontinued.