Earlier this week, Facebook unveiled a new service called Marketplace, which lets users buy and sell stuff to others in its network. It's not an original idea: eBay, Craigslist, and Amazon have been offering similar services for years. In fact, Facebook launched an ill-fated sales feature under the very same name back in 2007. But for those with unwanted vinyl records or a Microsoft Zune media player, Facebook Marketplace is yet another place to shop their wares.

What Is It?

Marketplace allows Facebook users, 18 years old and up, to post pictures of their garage sale items and collectibles and browse items offered by nearby sellers as well. The sellers set the price, but would-be buyers are welcome to counter with another offer.

The feature began rolling out slowly to Facebook's mobile app users in the U.S., U.K., Australia, and New Zealand, with a desktop version and other locations to follow in the coming months. Right now, users can find stuff like a factory-unlocked iPhone 6 for about $350 and a lot of vintage cameras for $20. The search results can be filtered by product category and the proximity of the items (anywhere from two to 100 miles away).

iPhone users will find the Marketplace icon inside the Facebook app, at the bottom of their screen between the Groups and Notifications icons, where the Messenger shortcut used to be. (That now sits on the top-left corner beside the search bar.) Those on Android phones will find the icon near the top of the app, with Messenger on the right-hand side of the search bar.

Why Should I Use It?

With more than a billion monthly active users, Facebook is an inviting place to offload unwanted goods. In fact, lots of people have been using the social media network's Groups function to create mini marketplaces in recent years.

"More than 450 million people visit buy-and-sell groups each month—from families in a local neighborhood to collectors around the world," wrote Mary Ku, Facebook's director of product management, in a blog post explaining the new service. By comparison, in the second quarter of this year, eBay boasted 164 million active users, according to the data analysis company Statista.

As many as 100 million active iOS and Android app users will soon have Marketplace baked into their Facebook app. And the average user spends 50 minutes or more every day on the app.

What's more, the buying experience appears to be quite seamless. I found it easy to narrow down search parameters and the means for contacting sellers through Messenger is pretty intuitive. The Craigslist app also handles search pretty well, but the Contact button simply steers the user to a web version of the listing and leaves it up to the user to find the relevant information.

Selling was also pretty easy on Facebook Marketplace. Creating a listing and importing the image took less than a minute. And the Your Items tab makes organizing and managing your listings and queries to and from buyers relatively pain-free.

And, after a few embarrassing hiccups on the first day of operation, Marketplace's administrators seem to have cracked down on violations of Facebook's commerce policy, which prohibits the sale of prescription and recreational drugs, weapons, animals, alcohol, and explosives. As of Friday afternoon, I could not find any illicit items on sale.

In an official statement, Ku says Facebook "addressed the technical issue that caused this problem" and is "closely monitoring our systems to ensure violations are properly identified and removed as we gradually expand access to Marketplace."

What Else Do I Need to Know?

One of the service's chief selling points—at least compared to Craigslist—is that it sheds more light on both parties in a transaction, potentially cutting down on shady dealings.

"Marketplace adds immense transparency and credibility," says Rachael Powell, senior director of social media at the digital marketing agency Elasticity. "Facebook's innate social connectivity adds a layer of credibility when you're considering whether to purchase from a user."

Unlike on Craiglist, where the sellers are largely anonymous, Marketplace will supply you with information that lets you know who you're interacting with. It displays the location of buyers and sellers and users' public Facebook profiles and cover photos. You will also see if you have friends in common.

And, while not a guaranteed safety measure, knowing the amount of time the seller has been a Facebook user could help buyers weed out potential scammers. Just keep in mind that not everyone on Facebook uses their legal name or a legit profile picture.

It's also worth nothing that, unlike on eBay and Amazon (which mostly deals with new products), Marketplace charges no listing fees or taxes. However, it also doesn't offer the protection afforded by those two companies if, say, a product is defective or vastly different than described in the listing. Amazon and eBay provide return policies, while Facebook and Craigslist do not.

Marketplace operates a lot like a classified ads page: It simply lists items and leaves the buyers and sellers to negotiate the sales. The exchange of money and goods is left entirely to the two parties, much like on Craigslist.

And Marketplace doesn't have a feedback system like eBay and Amazon that allows buyers and sellers to rate their transactions. Instead, users must report suspicious or illegal activity to Facebook.