While I do love the visual transition that Google is making with its apps, including Google+, I think that Facebook's UI is near perfect. It has come a long way with negative feedback after every update, but the fact is that it works. Facebook has an iconic look and feel that people have come to expect, while Google is building theirs out out from scratch, pretty late in the game.
I came across an article on TechCrunch, written by MySpace Co-Founder, Tom Anderson, regarding Facebook's strategy, the new Skype partnership, and so forth. Read: Why Mark Zuckerberg’s First Public Response To Google+ Is The Right One. He points out may positives about what Facebook has going for itself.
The new "Circles" approach of organizing friends is something Google+ users will have to learn/get used to. We are generally good with adapting new methods, but there has to be an obvious "return" value. Why should we put effort into your new product when Facebook already works well?
"Facebook’s Groups were designed in a way to overcome the friend list problem. They’ve grown quickly, even if 95% of the user base can’t be bothered to make their own groups.... Create a Group feature, and let the 5% create the groups for the other 95%. It’s like Mechanical Turk, but we’re not getting paid." — Tom Anderson.
I've been using Google+ for several days now, and it's still confusing to me. I see absolutely no benefit to using Google+ at all, for now. I cannot communicate with whomever I want as easily as Facebook. More random people have added me in a couple of days than all the random requests from years of Facebook-ing.
One of Facebook's key goals is efficiency, as mentioned in the quote above. With no effort from most of Facebook's users, groups are built, allowing direct communication with specific people. This is a huge feature for me, and Google+'s "Hangout" feature is far from being an alternative. The same applies to Photos, Events, and Messaging.
Facebook has a user base of 750 million. Every feature that will ever launch will be instantly battle-tested, and as of today, Google+ isn't quite at that level. Some people say Facebook is ugly, but it seems they disregard critical usability points. Visuals alone will not build a social networking empire, but the combination of useful features will.
So, is Google+ actually useful to an average Facebook user?