Left largely unremarked during the controversy, but generally known, was that YouTube comments sections were typically a cesspit featuring the absolute dregs of humanity. The switch to G+ comments has improved the quality of comments tremendously. You'll still see the occasional hundred-post-long flame war on Israel-Palestine on a video about ducks or whatever, but the percentage of non-offensive and even useful comments is much higher today than it used to be. I often read the comments, and occasionally I even find them useful – perhaps pointing me to an interesting related video, or raising some background information that I can go away and verify.
There's one exception to this general rule that I came across tonight. In the pre-G+ era, the saddest place I ever saw on YouTube was the comments of Mariah Carey's One Sweet Day. Almost all of the comments – literally 95% or more – were RIP messages to lost friends or family. Page after page of people finding some comfort from the song and leaving a little personal message. I don't know what motivated anyone to express their grief in the form of a YouTube comment, but the memory of those comments makes me tear up even now.
There's still some of that in the G+-style comments to One Sweet Day, enough to make me sad if I scroll through enough of them. But people posting the song to Google Plus are often not leaving a comment at all, or perhaps snarking about the evolution of Carey and pop music more generally since the 1990's.
A little bit of good Internet has been lost.