As someone else mentioned, I find the signal to noise ratio to be much higher on G+ than facebook or twitter. I mainly use these tools for two purposes, keeping in touch with friends and following interesting people and topics.

Facebook wins for the former as most of my friends still aren't on G+ or twitter, however, most of the activity is uninteresting checkins and the like.

With twitter, I have followed people I am interested in for topical content, but I mostly see personal tweets and find myself quickly scrolling through them for an occasional interesting link. Also, the interaction is next to zero except for retweets. I don't think the medium lends itself to much more than light banter.

In contrast, on plus, the topical content is more informative often with interesting comments.