Actually I dont like Google Plus. It doesn't have any new features. The Cirlces is just like Facebook lists. Yes the chat and video options have advanced compare to Facebook but we are not using social networks for chatting and video conference. For that we already have skype.
G+ is not mainly whole social site but it is place with all services provided by google at same place.As G+ is has both kind of platform one is for business and one is for full entertainment. G+ has many features that can be helpful for all.
I think it's great that it lets the user categorize his contacts so easily. I also really dig the clearly arranged interface. I don't think that it will be a great danger to other social networks. of course google+ will have a market share but they won't take down facebook... I use both and I think facebook still is more interactive