I think the biggest thing in that article is the last bit. I'm willing to bet that of all of the public posts, there's more private posts. All of my posts are private, simply because I like it that way, but even then, not everyone sees everything.
Ghost town? Not at all. I have plenty going on within my stream, and if I tried harder/had more time, Google+ would become very busy for me.
I am looking to use Hangouts more though. My limited experience in them has been positive, far better than Skype.