I used it at my last company before the JIRA brigade took over, and I"m pushing it at my current gig. My typical JIRA cycle goes like: I use a simple PM tool. PM's insist on JIRA, because "features". PM's can't figure out how to do simple things (because JIRA). PM gives me admin rights. I quit. That was my last three companies. Anyways -- Clubhouse is more limited, focused, opinionated. The UI is snappy behaves exactly like I expected as I learned it. It feels a little cluttered at times, but unlike JIRA everything seems to work in the ways I expect. It has some interesting constraints (stories belong to epics belong to milestones, so you can't put a story directly in a milestone) but overall I like it much more than JIRA.

My tl;dr for Clubhouse is that (imho) most software shops would be better off using it, or something nearly identical to it, instead of opting for JIRA to turn that one knob they just can't live without. JIRA works well if you need complex workflow management and can hire people to administrate that _as their full time job_.