I'm looking forward to them. I usually like to get my games from GOG whenever I can. The only bad things I've heard is that they can be slow getting back with devs. What else have you heard?
Just that the process is pretty slow and the effort you need to put in is not always worth it. Itch is a pretty straightforward process, while Steam has by far and away the biggest reach, so that's why I've been focused on those two platforms and my Patreon of course.