There's a persistent myth that Facebook Group is the same as Google+ Circles. They are nowhere near each other. In fact, Google+ does not have the equivalent of Facebook Groups, unless you count in the older Google Groups.
Facebook Group is closer to Google Groups or Yahoo Groups or any one of the dozens of forum-type sites. You create a space in which people join. It creates a venue. Google+ Circles is much closer to Livejournal friend filters. You have overlapping contexts but no single, formal venue that you join. Psychologically and sociologically, it works differently. It takes a lot more engineering work to get circles implemented than it does Facebook Groups (as it is implemented today).
I've been revisiting sending messages to specific groups of people in Facebook, outside the Groups context:
- To send to specific people on Facebook, you specify them directly. There are no pre-defined lists of people. Further, you have to jump extra hoops to do this, by clicking on the tiny lock icon, and then clicking on custom, and then typing in the names of the people you want to send this to. You have to do this for every single post you want to send out on a limited scope. Clearly, the Facebook UX designers want you to send it out to everyone.
- You can do the equivalent of private message to a group of people for an ad-hoc group. The last time I tried that, I hit its biggest limitation. I wanted to add more people into the running thread and it would not allow me to do that. Fortunately, everyone involved are current Livejournal contacts and we moved the conversation over there. Google+ does not allow you to add more people or circles to a running thread, but it does allow you to add more people into the circles which are dynamically computed into existing threads. As it should work.
- Google+ Profiles lets you specify exactly which part of the profile is viewable by which circle + people. You may not want your business phone number available to your drinking buddies, and you may not want your home phone number available to your business contacts.
- Google+ has a tool that lets you view what your stream looks like to other people. Admittedly, this is somewhat buried in the site.
- saurih brings up a very good point, "it doesn't matter how good your security is if people refuse to lift a finger to use it." A large % of the people in my circles are using it as public posts -- either thinking it in terms of Twitter-public, or they don't really care to. One of the people on there twigged on an insight: public posts on Google+ are meant for things that are relavent to everyone. People tend to post publicly and ignore much of the circle functionality; and as such, the interface will feel clunkier because you're not making full use of it.
On the other hand, all my friends who are expats from Livejournal and had been itching to ditch Facebook for something that provides this granularity of social contexts have set up the different streams.
In any case. Google+ scratches an itch I had. I'm glad it is here. It is the right tool for me, whether or not it is the right tool for the vast majority of Facebook users.