First off, I'd like to thank two authors who don't know me from a hole in the wall, Julie A. Lindsey and Mary Robinette Kowal, for inviting me to Google+. To reward their graciousness, I began stalking them almost immediately.
First things first: the layout will look pretty familiar. Google+ isn't exactly reinventing the wheel. You have a wall. People post on that wall. You post on other people's walls. You have a news feed of what all of your friends are posting. Photos, videos, notifications...
You don't friend people in the same manner. Instead of sending a friend request and waiting for confirmation, you place a person in any number of Circles and begin posting on their wall. My guess is that a user can turn that off, but it seems that everyone on GooP (that's what I'm calling it until someone comes up with something better) has a public wall, for the time being, at least. The other person will receive a notification and can choose to put you in one of their Circles or not (Hey, Neil Gaiman, put me in a Circle. I'm hilarious, dammit!).
Circles allow you to dictate who gets to see any given status. If you want to bitch about your job (still inadvisable on a social networking site, by the way) you can specify that only your "Friends" see it, and not your "Work Buddies." The benefits of this should be obvious. I understand that FB has some sort of group list function, but in my experience it's decidedly un-user-friendly. GooP's Circle function is much easier to both build and use.
As far as posting, both networks have numerous similar features. GooP has its version of the "Like" button called "+1." You can also choose to "Mute" anyone's post; this will remove it from your feed, but you can choose to unmute it if you wish to bring it back. This is identical to FB's "Hide" function. But...and this is big...GooP has something that FB users have been clamoring for: the ability to edit a post at any time, not within the window of just a few seconds that FB has now.
Now here's where GooP leaves Facebook in the dust: Hangouts and Sparks.
Hangouts enable a group of up to ten people to video/audio conference or chat together. It's fast and easy to do. FB is about to add Skype functionality, but initial reports of that are underwhelming.
Sparks are a clever tool that lets you "find stuff you're interested in." Simply put, you search for a topic, click the "Add Interest" button, and you will have a continuous feed of related news. My current Sparks? New England Patriots, Stephen King, Fiction Writing, and Zombies.
Shut up. :-)
If not for Sparks, I wouldn't have found out that Stephen King and his son Joe Hill might co-write an episode of "The Walking Dead" during Season Two. If you're me, that matters.
I'm thoroughly impressed by Google+, and I can't wait until it's open to everyone so we can truly see what it can do. I will definitely be active on both Facebook and GooP. In all honesty, if I could pack up my stuff (i.e. Facebook friends) and move in to GooP, I would do it right now and never look back.