Google+ is in some peoples opinion, including mine, the best of Facebook and Twitter combined.
Initially access was by invitation only but as of this week anyone can set up a G+ account and just like Facebook it is free.
Facebook has just this week caught up with G+ in that both allow the restriction of your post visibility if required. In G+ you set up groups and so you could have a Family Group, Friends Group, Work Group etc etc a group in G+ speak is a circle.
G+ is fully integrated with Picasa and so images can be automatically integrated from your Picasa gallery and displayed in your post. The quality of the photos is therefore much better than Facebook.
In a very short period of time, bearing in mind that initially G+ was by invitation only, it has gathered a large membership of photographers worldwide.
Like anything new it will take time to build a large membership but it seems to me that G+ is building a large membership at a pretty rapid rate.
Will it replace Facebook and Twitter? In my opinion probably not BUT I think that it will become a popular place to be.
Give it a try and if you don’t like it you can always delete your account.
Scott Kelby has also written about G+ on his blog.
There is an excellent How to Use Google+ on Colby Brown’s blog.