I bought my Grand Prix used from the original owner. It was loaded with sunroof and "heads-up" display on the windshield. I loved this car. It had 50,000 miles on it when I purchased it and it had 130K when I sold it. I never had any engine problems except that the intake manifold gasket was leaking due to a known issue caused by GM's Dexcool antifreeze. Coolant leaks are a common problem on GM models from that time period. It was going to cost me about $700 to have it repaired and the car is only valued at about $1500, so I decided to trade it in on a new vehicle. The car handles well and the 3.1 liter engine delivers plenty of horsepower.
"Heads up" display is my favorite feature without a doubt. I don't know why they don't put this on more cars. I love the body style. It's a sharp looking car.
When the headlights go out, you have to change the whole lamp, not just the bulb. And, of course, the bulbs are $25 apiece and don't seem to last very long considering the cost.