You get an email about activity, you see activity on the YouTube comments, you see activity through G+ notifications -- and none of it makes sense.
Did this action occur on G+? YouTube? Is this a reply to something somewhere else? What the hell is going on?
I don't mind G+ integration at all, and I think it's a good step forward, but it is simply not working well on services like YouTube at the moment and impedes use.
Also, spam control for comments is just broken. Scroll down, hover, maybe the yellow "review spam comments" box appears and maybe it doesn't. I found it interesting that G+ shares were very, very frequently marked as spam.
a) why G+ integration was a great idea, and
b) how thoroughly Google screwed up the implementation of that great idea.
If somebody comments on your Youtube post? You want to know about it. If somebody posts it to their public G+ page? You want to know about it. If somebody comments on that G+ post? You want to know about it.
Giving you a single place to drink that fire-hose of information? Great idea!
Intertwingling all those concepts together into a single mixed-up unfilterable slurry of commenting? Holy crap no wrong don't do that.