I always wanted to order a factory model, mine was indeed one of those 'loaded premiers' lol, but its what i wanted and unlike a lot of other vehicles i can be sure that this one will last long after the payments are over.
The Shark fin should not be a concern for you as Gm made running changes, one of the advantages of having a later model in the cycle. It would leak into the drivers side visor area and drip onto the floor. It was caused by the gasket under the fin having a drain hole facing the wrong way, which was up, gm just changes the antenna and the gasket with a new one with the hole now facing down towards the front so the water can drain out. The AC condenser should also not be a concern as yours should have the new style, there are lots of threads here on the forum so you can browse that one. Lots of water on the ground is a good sign that yours is working well. My Pass side rear window fm/am antennas have never given me any issues as the sound is good. The sat does drop out near cliffs and under bridges but that is line of sight issues and not a problem.
As far as issues go, all vehicles will have some to some degree but with time parts and experience will win out. I remember the days when the old mechanics would shake their heads at the vehicles that do not have carbs, now we look back on those early fuel injection days with fondness and that will happen in ten years when we go to repair our old electronics.