Here's what the first users are saying about Facebook's Slack competitor

Not to scroll through News Feeds full of viral videos and baby photos, but actually to streamline their workplace communication, through its new enterprise product, Facebook At Work.

By vying to be the main internal communication tool for businesses, Facebook hopes to tap into a lucrative new market with a stable base of customers and a steady stream of fresh revenue.

But Facebook is competing against other established products like Microsoft-owned Yammer and Slack, the super-hot startup that has become one of the fastest-growing business apps of all time.

And Facebook's greatest adversary in the workplace may be its own reputation: With many companies having spent years trying to stamp out on-the-job use of the social network by employees, Facebook must now convince businesses that it can improve, not kill, worker productivity.

Early signs are positive. Facebook launched the platform in beta testing last January, and it now has over 450 companies trying it out - including big corporations like Heineken and the Royal Bank of Scotland - with more than 60,000 on its wait-list.

Facebook originally said it would officially launch At Work for the public by the end up 2015, which didn't happen, but the exec leading the efforts, Julien Codorniou, tells Business Insider that the launch date is "very close."

One of the companies testing out the service told Business Insider that Facebook reps alluded that the service would launch out of beta in late summer or early fall.

We talked to a handful of companies that are currently using the test version of Facebook's workplace edition to gauge their first impressions ahead of the big launch. Their feedback shows some of the opportunities, as well as the challenges, that Facebook will have to address as it moves ahead with one of its most significant strategic moves.

Too social?

The business-friendly version of Facebook presents a much more serious face, with a gray color-scheme that sets it apart from the familiar blue-colored social network.

Facebook At Work has no ads. And it's strictly for work. Users get a separate account for work, with none of their personal Facebook friends or messages mixed in with their professional identity (although a user can easily toggle between the work and personal version of Facebook with the click of a button).

But for people connected to the business version of Facebook, breaking out from the type of behavior common the consumer social network, is not easy.

"The biggest challenge for us is taking it from the social 'fun' experience to doing actually work on it," says Ben Sand, VP of global operations at the marketing company Kenshoo, who has used the product for about a year. "I would be lying if I said that we were not struggling with that even today."

Part of the social problem, Sand says, is that people have become accustomed to posting pictures on social media apps. That means employees respond well to images but often ignore lengthy, text-based announcements.

On-boarding ease

The familiarity of Facebook gives it one big advantage over competing workplace apps: everybody already knows how to use it.

Matthieu Stefani, founder of a startup called CosaVostra, said that it took his team about six months to get everyone onboard with Slack, whereas people flocked to FB @ Work right away, because using it was so instinctual.

Alicia Taggio, who works at the travel company Flight Centre, says that since the company launched FB@W in early April, 80% of the 1,000+ Canadian employees are actively using it, which is "way better" than she would have expected.

Her team immediately starting setting up different Groups, which is the main way that employees organize themselves in FB@Work. Companies can make separate Groups for different projects, teams, company announcements, and social topics.

"It could seem a little overwhelming at first, being part of so many Groups," Taggio said. "But then you figure out how to add certain ones to your 'favorites,' easily check which ones have new updates, and see trending posts."

Employees have main News Feeds too, where a personalized algorithm, just like on regular Facebook, that will pull highlights from different Groups.

"It's a big challenge to make sure that people see the most important information that matters to them," Facebook's Codorniou says.

Less immediacy can be a good thing

Facebook's business version also includes "Work Chat," which functions like Facebook Messenger and allows employees to have private or multi-person conversations, including via video.

But Facebook at Work's core product is designed so that users can check-in periodically without being constantly connected, or interrupted.

That's a key selling point for people like CosaVostra's Stefani, who find

Miranda Hobbs, of commerce platform iAdvize, says that 50% of employees check Facebook @ Work several times a day, while 35% of the company's employees have the tab open all day.

"The goal is really to extensively cut down the amount of internal emails we're sending," she says. "We've really been encouraging people to check it at least once a day and join the top five Groups."

For example, admins can tell how many (and which) employees saw each post, when, and on what kind of device, as well as who the most "influential" users are, based on how often they post, comment, or like things. Weber Shandwick, a public relations firm which is trialing the product, says that its CEO is actually in the top five most influential users.

Free - for now

Facebook has not yet said exactly what it will charge businesses to use its new product.

Previous reports have said Facebook planned to charge only for certain premium features and for integrations with other, third-party apps. But one company that Business Insider talked to said that it had been told that just to use the service - regardless of integrations - companies would pay a per-user per month fee. They'd been quoted a cost between $1 to $5 per user.

For comparison, Slack's standard package costs $6.67 per month and $12.50 for its Plus program.

Stacking up to other services

One of the most reoccurring complaints we heard from companies about FB @ Work was the lack of integration with other services that they depend on, like Asana or Salesforce Chatter. People we talked to assume those add-ons will come eventually, though.

Sand says that Kenshoo uses At Work as its main internal communication tool, but notes how it seems like a big missed opportunity for Google.

"Funnily enough, Facebook At Work is amazingly similar to Google+," Sand said, mainly in its focus on segmented Groups. "We're a Google company - we use Gmail and Apps - but Google+ as a tool just didn't take off for us."

Here's a little peek at how FB @ Work looks: