There was a traffic spike of more than 1000 percent after Google+ opened to the public, but it wasn't clear whether that would last.
It's one thing to generate interest for a new product. It's another entirely to truly compete with a market leader like Facebook. Even with their September gains, Google+ wasn't even a blip on Facebook's radar.
According to Chitika, an advertising analytics firm, that spike was short lived. In fact, it appears the influx of new users had absolutely no long term affect on traffic, which later returned to a level similar to the private beta phase.
With Google's resources behind it, Google+ will no doubt get more attention and additional development. It's not done yet by any means.
But it also isn't the Facebook killer Google executives envisioned, at least not yet.