GitHub, GitLab.com, and self-hosted GitLab supported all in one workspace (the initial plan was to support one provider per workspace so we have really come a long way).
Per-repo channel routing, user mappings, and Slack @mentions. No more missing that one comment on your PR from 4 hours ago.
Workspaces, team invites, and free / Team billing. Thank you Stripe for not making me handle billing myself.
Docs and install guides at /docs (that is where you are right now).
Future plans include more login options, labels mapping, more configuration options for what you want in your Slack messages and much more!!