We should all start using Google Plus more. Still don't understand why people won't make the switch.
The rest is news and updates I already saw on Facebook, Twitter, and RSS feeds. This is with a few carefully curated circles. I culled a few people out for flooding me with uninteresting things, but G+ hasn't removed their posts from the stream. The rest are people who either don't post at all or don't post often.
I'm pretty sure it depends on who you follow, it only takes a minute to search for a couple of your interests and follow them but worth it
I am subscribed to 100+ RSS feeds that have no corollary in Google+ and likely never will.