What? You thought Google or Facebook were software companies? No, those are marketing and advertising companies. Lead generation is their business. The free software is just the foot in the door. And a nice foot it is.
As for the Youtube commenting system which all those who want to be derisive about G+ are quick to point to, they fail to mention how Youtube comments weren't that great to begin with and that the G+ comments they refer to are the ones rolled out immediately after the change, they omit mentioning and don't account for the numerous iterations the system received since then, and they haven't bothered to check on the comments situation since then because it would destroy their strawman arguments.
I can't keep myself signed in. Well, kind of; g+ UI was designed by trolls, so what actually happens is that I appear to be signed in until I actually try to do anything, at which point I'm asked to sign in. Sometimes I even sign in, try to check my notifications, and am asked to sign in again.
Anytime I post a comment "Also post to Google+" is pre-checked. I can't make it unchecked by default.
I have had a YouTube account for years. Since the changeover, I receive more spam from random strangers every week than I did over the rest of the account's lifetime combined. I now also get newsletter spam from YouTube itself (I'm now looking at an email entitled "Well... these love songs are awkward on YouTube", like that is something I would ever want). On the bright side, I clicked the unsubscribe link and unlike the last three times, it didn't throw a server error, so I'll see if it takes.
Despite never flagging any of the above as spam, my Gmail spam filter has started catching my subscription emails as spam. That is, the legitimate communications from YouTube that I specifically asked for are the ones getting killed, as opposed to the scummy newsletters I was autosubscribed to and the new spam vector that is g+.
If this stuff seems minor, keep in mind that it's all the fault of something that I didn't ask for, never wanted, and actively tried to avoid.
Why doesn't that make sense? Is a YouTube user naturally a Google Drive user? A Gmail user naturally a Blogger user? This seems to only make sense to Google, and not their users.
I don't know how much overlap there was between YouTube users and Google account users, but Google merged the two simply to boost the profile of Google+. People who wanted to comment on YouTube videos with their Google+ pals and their real identities were already doing that -- on Google+. The forcing of Google+ on YouTube offered no discernible benefit to YouTube users that could not have been offered while maintaining YouTube as a distinct social network.
As a Google+ user, the utter disregard towards YouTube and its distinct identity severely annoyed me.
So net result of the G+ 'experience' is that I lose services and have the quality of those that remain impaired.