The old system had flaws but it worked. Firstly, I'm not against G+ integration if it meant both products were improved. However, this change looks to me like forcing a whole lot of Reader users to begrudgingly use G+. Reader's social features were not improved; only removed other than a "share to G+".
Not replacing the following system with an interface into G+ so that you can view and comment on friends' submissions from Reader is annoying. Reader was my social network. Why are they forcing me to go open G+ in a new tab everyday to see if my friends had shared anything? That's the _very_ reason I use a feed aggregator. Google doesn't provide any way to view streams in Reader (to my knowledge. I would really love to be wrong here); the only way is probably to use a third party method with no guarantee to not break every time Google touches the G+ code.
Edit: additionally, when viewing shared items on Reader, Reader tries to get the article or picture in. Now, not only do you have to go to G+, it only gives you a link rather than try to fit the article or picture onto the post. Irritating.
- You interacted with that subset of your friends (and their friends) that cared enough about reading to use this weird software.
- You could read your hand-selected feeds, share items and read others' shares in the same place. It was social reading. Now the reading and the social aspect are divorced.
Divorcing the social aspect from the RSS reader makes sense. Social reading should be a subset of Google+, not a layer on top of Google Reader. Google should improve the reading articles aspect of Google+ (Sparks or whatever seemed DOA), yes, but the overarching concept is very sound.
* you could view the shared items and their comments in the same interface.
Not sure how G+ handle this, but when multiple people share the same article, it will often show only once in Shared Items.