DoomSooth: No Connect for me, please. I don't want to link my GOG account to any others.
Well, technically speaking you would link your Steam account information to GOG, not the other way round.
Steam wouldn't get any information about your GOG account.
I think GOG Connect was great.
I was able to get several games to my GOG account that way.
It was especially useful in getting continued access to some bundled games where the original site no longer exists.
I got many games through the route: Indie Royale -> Steam -> GOG.
GOG Connect was the only "integration thing" on GOG that I found useful.
GOG Galaxy and other stuff I have never even attempted to use.