pds41: 100%. GFWL wasn't DRM in itself; it was basically an overlay with social features (that also let you do a bit of account management on the same computer). I don't understand where all the hate for it came from - and I was always shocked that when it closed down and games moved to Steam that people were celebrating.
There was a lot of disinformation going round about it at the time - even (formerly - I wouldn't recommend anyone touches PCGamer with a barge pole these days) reputable publications like PCGamer hadn't done their research and just parroted the line that when it was turned off, games would stop working. At the risk of sounding like a conspiracy theorist, it wouldn't surprise me if a lot of that was planted by Valve to try to undermine competing systems.
Well, you could not call it exactly "stable". Often you needed multiple attempts to log in.
One of the biggies - GTA4 - had severe problems with their own social club. But instead of blaming Rockstar, the GFWL was blamed. And you know how Steam fans are. MS trying what their favorite Shop does? That's pure insolence!
As part of GamesForWindows it's purpose was also to define standards of how Windows games had to be made.
Microsoft had their chance back then and blew it. Now with XBox Live I think they got it right, but too little too late, if you ask me.
And they still like to treat Windows computers as "devices", having specific installation directories, at least now they let you chose the partition and don't put the game files into encrypted directories like the Windows store does.