One of my big takeaways after using this for a while as an alternative to Steam is that I really miss the community features. Galaxy 2 does a decent job of trying to integrate all your accounts as well as setting up its own community hub, but it's not quite the same as jumping into a Steam forum, checking out your friends' screenshots, reading user reviews, and going through curator recommendations. I think it could help a lot if they allow you to at least import friends from your other gaming accounts. Right now, all you can do is pull from Facebook for some reason or another. Hopefully they'll do something about that soon.
I also think that the library is basically a web page or at least it feels like one. It's not quite as snappy as Steam. It's just a little sluggish, kind of like Origin. Some of the great features Galaxy 1.2 had are gone in this version, too. I've got a long notepad file for the feedback form that I'll be filling out later. There's still a lot that could use improving before I'd start using this on a regular basis.
It's a very solid foundation though. I think that if they really nail this, it could be a great spoke off of which you can access your library in other places. And it already did what they were hoping it would; I started looking at and using GOG more often, even for new games.