Ranked in these QuestionsQuestion Ranking
Pro Highly customisable and powerful workflows
You can provide custom workflows for all the different types of issues. For example you can make features go through a flow of "Backlog -> Needs design -> Built -> Needs QA -> done" with bugs going through a different flow. These workflows are very powerful as you can configure them to automatically assign your QA lead when moved into the needs QA state. These features do require some learning curve to set up, but make the tool a lot more efficient to use as things like managing who is assigned to an issue can be automated.
Pro Has App Marketplace for extensions
Pro Powerful tools for issue management
Issues in a current sprint are viewed in a Kanban interface. But for the issues not in a sprint Jira provides a compact view with many powerful tools to search and filter the list. You can create custom filters such as "Show me all issues not yet designed that are assigned to me" and a variety of other tools that make dealing with large backlogs easy.
Con Slow to use
Every view switch and action takes a second or two. Doesn't seem too bad when you first start using it, but the UI is complicated enough that you need to manipulate it a lot and all that time adds up.
Con Merely a thin interface to a massive database
Too many configuration details, too confusing, too difficult to search and modify numerous tickets.