Trunk gets moisture inside. Still don't know where from. It's not a lot, just some on the deck lid, like you get a fogging effect for windows.
Theft system goes off now and then. The car won't start for 10 minutes. "Cut yellow wire from key switch and put it on a switch". Theft light will be on, but you can start your car, then flip the switch and turn it off.
Blower for the heat and A/C stopped working on the #1 & 2 setting. Need to replace the resistor.
A/C light goes off and on by itself. When it is off, the A/C blows hot. "Took the controls out and apart, cleaned with alcohol and traced the contacts with pencil lead; now it works fine".
The A/C clutch will not disengage fully when the A/C is not running, and makes a lot of noise.
Grinding on the clutch needs replaced, but A/C still works great. I'll fix it when I no longer have cold air in the summer.
P.S. in the winter you will hear it more, because it is cold already, and the clutch will not engage unless it warms up outside above 60 degrees.
CD player didn't work. Just keeps saying ERROR. "Took stereo out and apart. Found the ribbon connector was broke. Soldered a small wire from point A to point B where the ribbon was broke, and now the CD player works fine".
The gas gauge was flipped all the way around to the little tab below "E". Took a small drill bit and drilled a small hole thru the plastic just under the gauge, and used a paperclip to gently pull the needle over the tab, and now the gauge works fine. Just don't disconnect the battery; if you do, it will do it again.
Check engine light came on. Took to Auto Zone. Had them check it. They said the gas cap, so I got a new one; solved the problem.
Great car overall.
GM could have done better with the idiosyncrasies, like the A/C light goes off and on.
Theft system not working properly.
The blower resistor.
Gas gauge flipping around when the battery is replaced.
But I have to say I have seen worse cars, and for the most part, with a little time you can fix most of the issues yourself. All you have to do is know what to ask and where to ask.