GoG works on making older games playable on modern OS's, but outside of that they release a few indie titles and some AAA titles here and there, but not to the same number that Steam has going for it. GoG also lacks full mod support like Valve has with Steam workshop. Currently on Steam, there are two ways of modding a game:
1. Mod support via the steam workshop, where you can pick and choose what mods to subscribe to and have it downloaded for you.
2. Download mods from an outside source via that game's modding sub forum area (via the game's discussion hub).
Yeah that's one thing I like about Steam. I used to do that with gun skins for Insurgency. I'm just curious because most PC gamers I know love steam despite it's most known issue, so I was wondering how he felt.