To be honest, Google Circles is isomorphic to groups in your local address book, with the exception that you aren’t holding onto an e-mail address but rather an identity. That permits, for example others to update their contents whilst keeping the same identity throughout; a kind of distributed address book, if you will. Except that unlike Buzz, it’s not integrated into your mail contacts.
Buzz screwed up not because it was integrated with your contacts, but because it auto-exposed your contacts to the wide world, based on frequency of mail exchanges. Had Buzz not exposed contacts automatically, but rather used an ‘opt-in’, like Google Circles, it would have been much better (and essentially what you’ve got now with Buzz). But ultimately, where we are now with Circles is the same as we are now with Buzz; the circles exist for your categorisation purposes only.
That’s useful when (for example) you have a small group of people that you define, such as close family members or members of a local club. But unfortunately for Google+ social relationships aren’t reflexive; if you follow someone, it doesn’t imply they follow you (or vice versa).
I post about varied topics on my blog. Eclipse used to be a mainstay, but has dropped off over the years. ZFS used to be another before it forked off. These days, I’m most likely to write about Git – but there are always other topics (like personal health updates or IPv6) that I write about occasionally.
I’m pretty sure my blog as it stands correlates exactly with one person’s interests – mine. (There can’t be that many people who are bothered about my health, and I know my wife has no interest in Eclipse.) That’s why the various feeds I offer are useful; it allows someone to take a feed of just the Eclipse related items (which then gets fed to Planet Eclipse). Those interested in my Git Tip of the Week series can follow their own feed, without having to read things that aren’t interesting to them.
All of this works because which feeds to consume are a self service. I don’t define a list of people and say “Person X is only interested in Topic Y; I’ll ensure they get all those items.” Instead, Person X can choose whether to subscribe to Topic Y (or X or Z) on their own terms and time. People’s interests change over time; whilst they might be interested in Topic Y to start with, they may gain an interest in Topic X (and cease to be interested in Topic Y) and so adjust subscriptions accordingly. It shouldn’t be necessary for me to be in the loop to make that decision happen.
Finally, the followers and following are asymmetric; or to put it another way, the two sets are unlikely to be a complete overlap. There are people I follow who don’t follow me; there are people who follow me whom I don’t follow, and there are those that follow each other. The same is true of blogs; this post is likely to be read by some of the bloggers that I follow, but equally, it’s likely to be read by other bloggers that I don’t (or even who don’t blog at all).
Asking me to categorise all my followers is a waste both of my time and also of the opportunity for my followers to categorise themselves. I tag each of my posts so that people know what they are related to; this in turn fills the Eclipse feed or the Git Tip of the Week Feed or the OSGi Feed. And those that are (just) interested in OSGi can consume a tailor-made feed, just for them.
Google Circles, on the other hand, is only good for publishing to publicly, or to a small infrequently changing set such as family (family members don’t come and go that frequently). And in all honesty, unless a significant proportion of your family members are on Google+ already, there’s probably not a lot of point in even that.
What Google Circles needs is a way of defining publicly subscribable circles. I can create a few circles that are of interest to me (Eclipse, OSGi, iOS) but membership of those circles should be public. That way, I can publish something to just the Eclipse circle, and just those interested in Eclipse will see the information, just like they can today with my blog posts. It’s no good allowing anyone to follow me but then expect me to have to put them in a circle in order to get a customised feed for them; right now, it’s all or nothing.