Maybe it's totally unjustified, but I instinctively shudder seeing "UI" and "Atlassian" in the same context. Jira might be the only thing worse than MS Teams that I [am forced to] use on the daily basis.
I had the same reaction. But looked at this and it does feel quite nice. I think most of the pain of Jira is not so much in the visual UI bit but in the overall morass of clunky flows.