Circles were great! Google+ was among the least obnoxious social media platforms I have experienced.

I think it could really have replaced all the fragmented around Google comment forms, but it sure wasn't wise to force everyone on YouTube on it in such a shitty way. I think that initial public outcry was a significant stop to its velocity, yet it could have become moderately successful and very valuable long-term to slowly integrate all of Google's services. Just so many parts of the execution were questionable, including the mobile apps :\

Was the lack of a semi-immediate huge return the reason it was killed?

Heh. While I never really got into Google+, its "circles" idea definitely reminded me of LJ -- and it seemed like a great idea. It seems like it might not have been communicated very well to the audience.