I was an IC6 at Google when Google+ launched... From my perspective, I think partitioning the Google+ team into their own Dark Tower with their own super-healthy cafeteria that was for them and their executives alone was the biggest problem. IMO this even foreshadows separating off Google Brain from the rest of Google and giving them resources not available to anyone else. Google was at its best a relatively open cul…
I have to agree that the interface, and the "Real Names" requirements were the two biggest hurdles for me to even to start to like Google+.
I really liked the concept of circles, but whenever I did get around to using the social network, it never felt as social and engaging as Twitter. Even when I did find an intersting discussion, it was hard to keep track of replies. Reddit/HNews/Twitter have a tree-like structure for the comments, but Google+ was mostly flat, and hard to keep track of any debate.
I would lose interest on Google+ as soon as I tried to read a comment thread, and close the application altogether.