But within months, critics had panned the new service, pointing to user pages bereft of meaningful content and exchanges. They said the new social site just wasn't, well, social. It seemed as though Facebook had cornered the market - Google was too late to the party.
Perhaps not. According to data released this week by internet analytics firm GlobalWebIndex, Google+ is racking up large numbers of new users and continues to outpace Twitter as the world's number two social network, behind Facebook.
The reasons behind Google+'s growth - it now can boast 359 million active users, up 33% from 269 million users at the end of June 2012, according to GlobalWebIndex - are complex and tied to Google's effort to build a connecting layer across all its services, including search, YouTube, maps and other products. Log into one, and you've logged into the lot.
Google itself is tight-lipped about its numbers. Its last released figures were in December, when the search giant said 500 million people had created Google+ accounts.
But of this number, only 135 million were actively posting to Google+ pages. Millions more were using some of the service's features, such as clicking the "+1" button to show they liked certain web pages.
It remains far behind Facebook, which boasts 701 million active users, according to the report, though Facebook founder Mark Zuckerberg last year claimed more than a billion active accounts.
Still, the volume of Google+ accounts suggests naysayers were too hasty in calling its demise. Like many social networking services, Google+ has won over a devoted core of users.
One such convert is New Zealand photographer Trey Ratcliff, whose picture-centric Google+ page has nearly five million followers.
"It's nice to pop into Google+ to discover new things. Facebook is pretty good, but it's harder to discover new people or have more in-depth discussions around passions," he said in an e-mail exchange.
Indeed, this may be how Google+ will find its niche in the crowded social media world: Whereas Facebook is the go-to service for connecting friends, Google+ is more often used to meet strangers who share common interests.
Google+ acknowledged as much last year by adding its "Communities" section, which hosts a diverse mass of groups and lets users join a "hangout" - the popular group video service.
"We're extremely happy with our progress so far, and one of our main goals is to transform the overall Google experience and make all of the services people already love faster, more relevant, and more reliable," Google said.
But some observers remain sceptical that account holders are doing much on Google+, and see it as little more than a tricked-out sign-in service for Google's products.
Claire Stokoe, who works as social media manager at Mediaworks, a marketing agency in the English city of Newcastle, said she is doubtful Google+ will ever catch up to Facebook, but she warns clients not to ignore it.
"An authoritative Google+ account is one of the factors that will help you rank high on Google [search results]," she said, noting that a popular Google+ account was an important criterion in the search algorithm that ranks pages.
But she doesn't see the service expanding far beyond the business and marketing world - at least for now.
"Whoever I ask, everyone has a Facebook account. I don't know anyone who has a Google+ account unless they are in the industry, and that's because they have to," Stokoe said.
GlobalWebIndex's latest figures show that while Google+ is the second-most popular social networking service after Facebook, Twitter is actually growing at a slightly faster clip, increasing from 206 million users at the end of June last year to about 297 million today, a rate of about 44%.
The study also found that usage was growing fastest among older people, especially with Twitter, confounding stereotypes that social networking is for the young.