(CNN) -- Google's answer to Facebook went public on Tuesday afternoon.
For the past three months, Google+, the company's social network, was available only to users who had been invited by the company or by friends who already had access to the site.
"For the past 12 weeks we've been in field trial, and during that time we've listened and learned a great deal," Google's Vic Gundotra, a senior vice president for engineering, said in a blog post. "We're nowhere near done, but with the improvements we've made so far we're ready to move from field trial to beta, and introduce our 100th feature: open sign-ups.
"This way anyone can visit google.com/+, join the project and connect with the people they care about."
The update comes as many people who use the site are questioning its value.
"My Google+ home page is worse than a ghost town. It doesn't even feel haunted," wrote Rainbow Rowell, a columnist at the Omaha World-Herald.
Writing on the PBS blog Mediashift, Dan Reimold adds: "The stream of updates has basically run dry -- reduced to one buddy who regularly writes. My initial excitement about signing on and inviting people to join me has waned. Nowadays, I apparently get tired just thinking about it."
"I must be doing something wrong on Google+," Harry McCracken, founder of the blog Technologizer, wrote on his Google+ page. "It isn't 'worse than a ghost town' for me. It's active and pleasant, albeit lacking some of the initial rush."
Introduced in late June, Google Plus gained an estimated 25 million users by early August, although the company has released no recent figures on its membership. By contrast, Facebook has more than 750 million users, and Twitter has more than 175 million.
Google continues to add features to its social network in an apparent effort to spur growth and further differentiate itself from Facebook and Twitter. On Tuesday, the company announced a few more, including:
Better search for topics and personalities on the site: "Google+ search results include items that only you can see, so family updates are just as easy to find as international news," the company says.
"On-air" Hangouts: Google's group video-chat feature, called Hangouts, has helped it stand out from Facebook, which does not have a similar tool. Now users can broadcast these group chats to the public: "The setup is simple enough: just start a normal hangout, and you'll have the option to broadcast and record your session. Once you're 'On Air,' up to nine others can join your hangout (as usual), and anyone can watch your live broadcast," Google's blog post says.
Mobile Hangouts: These video chats now work on smartphones running Google's Android 2.3 operating systems. Support for the iPhone is coming soon, Google says.
To promote the new Hangouts features, Google will host an On-Air Hangout with rapper will.i.am on Wednesday.
What do you think? Now that Google+ is public, will you join? Or is yet another social network too many?
Let us know in the comments, or, if you're so inclined, join a conversation about this on my Google+ page.