I've tried it three separate times since they first released Galaxy, and it's never worked properly for me. As much as I like the thought of an optional client that can deliver similar features to Steam, Origin, etc, it doesn't seem to even be close yet.

What do you mean by "it's never worked properly for me"? Speed of games downloading was low, mistakes with time logging or what? There were multiple reports about speed issues recently due to some updates but in general it does what it should: installs games, run them and updates :-)

Among a few other minor glitches:

Sometimes it wouldn't start at all.
Sometimes when it was running and I tried to DL a game, I got nothing but a blank screen. Had to actually reboot the computer before it would finally work.
Sometimes it froze my computer and forced me to hard reboot.
Sometimes games wouldn't start at all.

The above issues occurred on two different PCs.

Sorry to hear, very unpleasant glitches :( Did you report them? I report Galaxy glitches on mantis.gog.com and dev team is very responsible.
I personally use Galaxy on Mac and it is pretty stable here, guess GOG lacks resources to develop it with good speed. The only thing we can hope on that they do they best and won't abandon it.

I haven't any problems with Galaxy except when I was forced to install it for The Witcher 3. Click NO and the installer cancels. Fuck you DRM! With games like The Witcher, Swat 4 and Divine: Original Sin, why would you say there are no top quality games on GOG?

You could be right.