Some thing driving the invites was the promise of some GB of free storage, which some people abused in creative ways via their APIs (I remember a fuse driver storing files as mail attachments ...)
And early on, despite a lot of anti-marketing that I still suspect was simply bought by FB, it was really great and vibrant. In its most original implementation, even.
Later on, the campaign of "complaints" about how empty it was got them to change bits of it, pushing "follow those people" on you that was filled with brain-numbing celebs and the like, and the magic was gone.
Whoever orchestrated that campaign should get a raise (and shouldn't meet me, as G+ was last web-based social media that I could earnestly use)
