I've got a parkerized SA 1911 purchased in 1992 (before Springfield started producing and marketing its "Mil-Specs" and "GIs"); the finish has held up superbly -- the pistol has seen hard use and much carry (in both leather and kydex holsters), and excepting a few small dings, looks almost new when clean. No rust problems whatsoever.
A recent production SS Mil-Spec (with the bright stainless flats) gets easily scratched and necessitates regular work with some Flitz. It's a good-lookin' piece, no rust problems here in the wet Puget Sound region. My Black Stainless is a range pistol only; used once with a somewhat dusty Blade Tech kydex holster, it picked up some scratches (personally, I just feel the thing's too pretty for regular carry).
I've also got an SA Loaded Bi-Tone Micro-Compact, and the nice bead-blasted finish on the stainless slide holds up wonderfully, looks great, tough finish and no rust problems.