Google + Circles acknowledges that we don't have one set of friends, but rather have many sets of friends. In Facebook, I have not found easy ways to communicate with one of my circles and not everyone. It may be there, but such groups have not been well envisioned so that it is easy for me to understand who I am interacting with or switch from one to another.
I think Facebook managed to recognize the strong force of Friendships and have modeled the rest of the world in those terms. I hope that Google is thinking hard about Friendships, how people manage friendships, and how they combine friendships with the other aspects of their lives.
Why am I always attracted to root for the underdog? In sports, I certainly love seeing an upset. In business I am attracted to the new guy with he hope that he corrects the mistakes of the established organization as well as deflates the arrogance of the dominant player.
I have looked briefly at Google's own help and demo presentations about Google + (catchy name: a one character punctuation symbol. Google seems to have looked at the essential aspects of Facebook and taken the most important concepts (friends) and gone to the next level with what you want to do with friends (have conversations, find information (Google hasn't forgotten its claim to fame) share some information, have live video conversations, share pictures easily) as well as the most difficult aspects of Facebook (e.g., putting boundaries around groups of friends)
Over the next several days, I will post my reactions to various features of Google + as I learn about them.