Google Reader circa yesterday provided an inbox-style interface for all of your content. A feed had read and unread items, and folders allowed you to compose macro-inboxes, and (this is the change) shared content was treated in the same way, if not better—new comments on this content would be clearly indicated, allowing for in-app discussions.
Today, Google Reader has made shared content a second-class feed. With the removal of the inbox-style interface, if you miss a friend's shared item on Google Plus (possibly buried in other items), it's gone. The closest you can come to a 'mark as unread' functionality is through a work-around: creating a memberless 'save for later' circle, to share items with. Furthermore, shared content isn't even visible within Google Reader.
I can't be alone in thinking this was a good interface for sharing articles. If anybody has an alternative RSS reader with this functionality, please let me know. I would pay for this, but I can see it being a tough sell generally.
Conesus, I think you've mentioned in a different thread that you have social features in the pipeline: is this something you're aiming at?