We started using it when the API was already available, and tied in error alerts from our integration server on day one. We've added a lot more since then, among them jenkins, monitoring thresholds on our AWS instances, etc.
Yeah, we're in a similar boat using it to monitor Jenkins, Datadog, Zendesk, JIRA, and a whole slew of other things aside from chat. It's hard to find a better bang for your buck if your company is bought into the ecosystem.