Hey There - I don't have a 2009. My mother had a 2007, which was a first gen CTS, and that had problems with the tie rods, and the amplifier for the stereo. The 2009 is a 2nd gen CTS. My father had two of those, a 2011, and a 2013. He totaled the 2011 in an accident, but put about 25,000 miles on it before it got demolished. He never had a repair only service on the car. The 2013 has about 25,000 miles on it, and it never had a repair either just service. The tie rod problem was fixed on hte 2nd gen cars. I checked. I have a 2011 CTS V, so it isn't comparable, but my car has had some problems with the drive shaft and the super charger. None of that applies to your car because mine is a V8. My car has 65,000 miles or so on it.
I rate the 2nd gen CTS as a better than average car in reliability from our experiene, but others may differ, and we never got huge miles on either of the two. That's all I can tell you. Best of luck, and enjoy your car.