I made one purchase from GOG when they were first getting started, I bought the Redneck Rampage collection. I was really looking forward to finally being able to play the game at a resolution higher than 640x480. That never happened because the game wasn't properly configured with DOSbox. Over the years I've checked GOG's forums to see if they ever bothered to address the problem, as of the last time I checked they hadn't.
Now I'm just sitting back and waiting to see if the game ever makes it's way to Steam. I purchased X-Com UFO Defense when it came out on Steam. They not only made it work they fixed the timing, the game would play too fast on newer computers, and added widescreen support. It plays on my computers as well, and actually better due to higher resolutions etc., than the day it came out.
Hopefully someday Dungeon Keeper, Redneck Rampage, and all the other classics will make their way to Steam and get the same treatment so I can just purchase them, install, and enjoy.