Larry Page, the co-founder and chief executive of Google, recently claimed that Google+ is becoming a force in social networking with 90m registered users.
But the Wall Street Journal has reported new data from comScore that suggests Google+ users are signing up to the site, but not spending anywhere near the same amount of time as on Facebook, which has 845m members worldwide.
The data indicates that visitors from PCs spent an average of around three minutes a month on Google+ between September last year and January 2012, compared to six to seven hours on Facebook each month during the same period. Mobile usage was not reported by comScore.
According to the Journal, many of the problems are due to the lack of differentiating points about Google+, beyond the 'Hangout' video calls for up to 10 people and the 'Circles' interest groups.
This has meant that Google is facing difficulty in persuading users with already well established networks on Facebook to switch to Google+ beyond just setting up an account.
"Nobody wants another social network right now," said Brian Solis, an analyst at social media analysts Altimeter Group.
Discussing people who already use Facebook, he added: "Google hasn't communicated what the value of Google+ is."
Various third-parties, including games maker Zynga and chipmaker Intel Corporation, have also expressed concern over the sluggish rate of activity seen on Google+.
However, Google vice president of product management Bradley Horowitz said that Google+ is designed to be more than just a 'destination' website, meaning its exact value and usage is hard for an external party to measure.
He said that Google+ was created to bring a "social networking layer" to other Google services, including Gmail and YouTube, as a value add.
On Thursday, Google will roll out changes to the way it manages information on Google Accounts, enabling personal data to be shared more easily across all of its services.
Google said that its update brings together more than 60 different privacy policies into a single approach, but campaign groups feel that could come at the expense of freedom.
> Google to have 400m members by the end of 2012, says report