All it's electronics, If it's been siting for that time and not been run, all the modules and electronics shut down. Then when you repower it (via starting), sometimes things don't come back alive all at once for some reason, setting body codes. I know if I don't go re-synch my keyfob (by unlock/locking the doors) every month or so while in storage, it shuts down all RKE (Remote Keyless Entry function), until I stick the fob in a slot in the center console for it to re-synch things. A lot depends on the options you get. Engine. Is it V6 or a Northstar V8? Is it just RWD or AWD? Does it have fancy shit like HID's and adaptive headlights, HUD, rainsense windshield wipers, Magneto shocks, navigation, heated/cooled seats, etc...?
If it's a Northstar, it'll leak oil from the cam covers if not already, eventually... ANd by now most of the head/stud issues with them had been sorted out.
Overall though, the car is a pretty solid car.
A lot can be gleened from here;
Forum dedicated to discussions about the mid-sized RWD / AWD STS luxury sedan, based on the Sigma platform.
www.cadillacforums.com