I have used Jira for a the lest few years in multiple companies.  One of the limitations to Jira as compared to to other, similar apps, is that you can only have 1 assignee at a time.  I would make things a lot easier if you could have 2.  That way if a company is using paired programming or wants to assign a Dev and QA up front, they both could be in that field AND their icons seen on the tile views of stories.