How Google+, Facebook, Twitter, LinkedIn and Tumblr Compare [Infographic] (very clear comparison)
via blog.hubspot.com
See especially the comparison of the photo site, 500x vs. Google+, on the issue of nudity in photos or not. (500x - yes, Google - no)
See also the first paragraph re. the rapid growth of Google+ compared with other social media sites.
very good article, especially in connection with dissidents against tyrannical governments