Google Plus has a serious flaw. It's summed up in this question:
Why are you following me?
I know who I want to share my "I hate my job" posts, and "Oh, my cat is so cute" pictures - but I talk about a wide range of things, not all of which you'll be interested in.
At the moment, I've got nearly 150 people following me - and I don't know which circle to put them in!
This is something Nik Butler and I have discussed.
Google needs to let people choose which circles to follow.
I imagine a UI which allows me to set a circle as private ("Work", "Family", "Political ranting") and set some circles as public ("Kitten pictures", "Industry News", "Political thoughts").
When you follow me, you can say "I hate kittens, but I love politics - I'll follow one circle and ignore the others."
At the moment, I don't have the time to categorise 200 people into what I think they're interested. And they don't want to be bombarded with QR codes when all they really want is LOLCATS.
So, come on Google, sort it out - let people choose which circles they want to be in.