Slack is an excellent workplace tool
We've used Slack at our company for about 2 years now, and it is an excellent workplace tool. If your office has offers telework and/or flexwork, or has remote employees, this is a good way to keep everyone 'together'. You'll want to set rules about when to use and when to be online and how to set your statuses, and minimum 'channels' to be in, and then it is a great foundation for communications. I would not say that this is a 'community platform' per se. Even with the basic paid version, data 'scrolls off' sooner than you'd think, and it is hard to communicate complex ideas or discussions in this format. Slack is better for quick sharing of info and collaboration. Great to use to 'get on the same page', checkins, etc.