I use Slack with a very small team for Sasstrology, and prefer it over email. Recently I read a blog post by Seth Clifford about using it as a personal information center. Since then, I've been mulling whether I really want to add an additional tool to the services I already use. Currently, I try to add just about anything text-based to Workflowy (I've also been using it to store bookmarks instead of using Pinboard) and I use Evernote for any other media (images, PDFs, screenshots, web clippings). Dropbox I only use to store json backups and other text that would not work in either Workflowy or Evernote. (I also use it to store Excel and Word docs that I need to use for Sasstrology business partners.)
The advantage of Slack is its integrations. I can subscribe to RSS feeds in channels, or use IFTTT to pull in information from many sources that do not already have integrations with Slack. Workflowy is totally siloed, and although Evernote works with IFTTT and has many integrations, I only really go there to access something specific or to do a search of my information dump, not to look at feeds or incoming information from outside sources.
I am also intrigued by the prospect of using a bookmarklet to quickly add links to a Slack channel. I have found three so far (none of which I have tried out): by Carlos Fonseca, William and Richard Peng, and Chad Etzel.
Slack allows a team owner to export conversations (excluding private and direct messages) in json format, so I can rest assured that I can use my data for other purposes if I no longer want to use Slack.
My main concern is spreading my information among too many services. If anything, I'm trying to use as few as possible, because I don't want to have to do a search of a handful of services to find the information I'm looking for. (CloudMagic used to offer a service that did a global search of many different services like Evernote and Dropbox and Gmail, but has since pivoted to email.) Nonetheless, I've already created a team of one, and I will report back if I find Slack useful for an individual.