I see this A LOT lately, and I have been using Plus since it started in beta.
You get what you put in to it. Period. If you only use it as a "megaphone" to self promote, who cares. If you use it like any other social network (to network and share) you will get something out of it.
Most of the people I see that say they don't get anything out of it, don't try. If you opened a Twitter account, followed 10 people, then sat and looked at it.... only sending out links to your own crappy content, you will get the same results.
I have found that by sharing content, videos, images, etc... and actually engaging with people like you would on FB or Twitter, you get more out of it.
That being said, Google has made it very difficult to get people to circle business pages, so I have learned a trick or 2 to help expedite that. I have a local home builder page that has over 300 people that has circled them, while our FB page only has 130 fans for the same builder. And yes, I have seen it help the SERP's.
We share industry related articles, cool architecture images, and add in a little of our own stuff for that builder, and we are starting to see some traction.
Bottom line, you get what you put in it. I am seeing local groups forming to work together to help promote each other, etc...
Still a very young network. Remember, you can't automate "social".... (not that that was question at hand, just like to remind people social isn't a "set it and forget it" metric in marketing)