In GFWL's defense, it and its predecessor were both developed without a full appreciation of the impact Steam was going to have on the marketplace. GFWL wanted to be a platform for selling MS games and Marketplace content. They didn't account for the fact that Steam was doing all that and more, better, when they launched. So GFWL was seen as redundant and purely motivated by DRM.
And again, to be fair, no one else saw it coming either pretty much. Uplay, Origins....everyone dropped the ball when competing with Steam, even with ample time to understand why it's been successful. GFWL just kind of went out there, totally unprepared for what the market was going to become and unable to offer users a REASON not to hate it.
This is almost literally beating a dead horse, but... the problem for me with GFWL is that it had minimum support and a lot of issues. As of recently, I had to go through some fun times with GFWL to run Dark Souls on PC. The issue? Endless "wrong version"/"updating" errors. I contacted MS support, and they pretty much shrugged and said they have no idea. Too bad.
The problem was that a relatively recent update has broken installations. It was a common problem, and required a full clear(harder than it sounds)/redownload/reinstall of the software. In addition, a core legacy service needed to be disabled in services.msc that otherwise prevented the software from connecting. This is not something a regular user should be expected to do, and definitely something to be covered by windows update - or at least technical staff.
Origin and UPlay are meh; their main downsides is that their respective companies have not made a full investment in server infrastructure and they go down randomly under load. That's just people trying to save a buck, and gets a lot of contempt from me. An excellent example would be Origin code activation servers going down on the first day of their ongoing HumbleBundle. Given EA's budget, and the HumbleBundle being promo material for them, this shouldn't be happening.
But back to GFWL. It's fine in it's own, but it has had many catastrophic downtimes, severe hardware incompatabilities, faulty patches that caused extensive operating system failures and games erased from player records. That's not acceptable for any software publisher, let alone a giant like Microsoft.