Like most of their IDEs, it's not about UX but about features. And on that point, they have done a lot!
Having used it for some projects as an alternative to JIRA, Trello, GitLab boards, and a few others that I tried, I think it's not perfect, quite hard to use for non-tech users, but much better than most of the alternatives.
The number of details/settings available is great compared to Trello or GitLab. The pricing/hosting is great compared to JIRA. The non-tech usability is much better in JIRA and Trello, but for a tech team, it has many small things/shortcuts like ones you already use in their IDEs which is really great.
There are hundreds of tools like this, and I tried maybe 20 or 30 of them; the thing is, there is no perfect tool out there, and there won't be as use cases for such a tool can be extremely different! YouTrack gets a lot of points right for a tech team from my experience though.
