We have internal jira, it's fine. It's Jira sure, I personally don't like the keyboard shortcuts (start typing when I hadn't clicked the box and it "does things"), and I'm sure some people set up horendous workflows, but it's fast and secure, upgrades are telegraphed well in advance, and it's far more reliable than say our SSO system
Operating it is a mess too, it's close to a full time job, I can't imagine recommending to host it like I do with communication software.