Based on pure metrics, it appears so. Google+ only has 100 million users that spend a couple minutes per month on the site compared to Facebook's 850 million users who are logged in for nearly eight hours per month. To be fair, Google+ has only been around for six months, but usage seems to have already plateaued. However, according to this article and tech evangelist Guy Kawasaki, Google+ may be a longer-term play and comparing it to other social networks may be a little misleading. Google+ is more of a social layer that is applied to the various Google products, making it a very different value proposition; Google+ is a collection of activity done on various Google sites, instead of a site that people connect to like Facebook, Twitter, etc. In this way, even though short-term success has been limited, there may be significant long-term success to come.
Read the article.
(submitted by Tom)