According to Slack itself, the messaging service is the best alternative to email. The New York Times' John Herrman explained Slack's perspective in preparation for the company's June IPO:
[Slack] claims to already have more than 10 million daily users and, in its listing prospectus, bills itself as the answer to bloated inboxes everywhere.
Slack delivers on its promise. Rather than be inundated with emails, Slack streamlines office communication. Slack is without frills and offers an organized messaging system for you and your coworkers. According to Herrman, Slack is "where and how work gets done." Slack lists a few of the ways people utilize its software in a "thank you" letter to users:
Thank you to the remote worker waking up halfway across the world opening Slack to find out what transpired as she slept. To the CEO using Slack to get people on the same page while on a different continent. To the intern getting kudos in a way the whole company can see. The farmer checking Slack to monitor feed levels.
Slack is often criticized for being an added distraction, but CNN's Seth Fiegerman argues that Slack also transports office culture into an online space, letting everyone participate in their own way.
At a time when more people are working jobs behind screens, sometimes remotely in distributed workplaces, Slack is the new office watercooler. It is the work environment you have when you're stuck at your desk for hours and can't hover by the glorious office plant wall or the craft beer taps in the kitchen.
Slack is both the break room and the announcement board. It is the conference room and your to-do list. Slack transforms everyday work:
Slack is where you welcome new employees with a procession of GIFs. It's where companies divide themselves between channels devoted to cats and channels devoted to dogs...It's where a company can bond with a party parrot emoji for every occasion: a coffee parrot and a beer parrot, a sad parrot and a fiesta parrot, a chill parrot and an exploding parrot.
But for some people, Slack is not the godsend it appears to be. Email replaced meetings, but Slack replaces quick questions. In an office where Slack rules, coworkers feel inclined to Slack rather than speak, resulting in quiet work spaces where desk-neighbors are having full conversations online, rather than turning to talk.
Others hate Slack because of its lack of formality. Email has its own etiquette rules, but since Slack looks and feels like texting, people treat it as such. Not everyone wants to use Slack as a chatroom, and unnecessary communication remains a huge distraction in offices that use it.