JIRA is the tracker for teams planning and building great products. Thousands of teams choose JIRA to capture and organize issues, assign work, and follow team activity.
Ranked in these QuestionsQuestion Ranking
Pro Integrations and plugins
It integrates well with a lot of other tools, including other products from the Atlassian suite. Plus there are a ton of plugins, including charting tools, screen capture, etc.
Pro Great reporting tools
Jira offers amazingly powerful reporting tools like activity stream, different graphs of opened and closed issues over time etc...
Pro Backed by a trustable company
Jira is developed and maintained by Atlassian, which is not an unknown venture, especially for developers. Atlassian has a great number of other products used by million of users worldwide, including BitBucket, HipChat, Confluence and Stash.
Each of these products have hundreds of thousands of users who use them daily and this has allowed Atlassian to garner a lot of goodwill from the dev community.
Con Locks you inside its own ecosystem
If you use Jira you are pretty much locked inside their ecosystem. For example, if you want to add a tool to your project management stack (like a wiki) more often than not you will have to buy one of Atlassian's tools.
Con Client application support
No free client applications; IDE connector development was discontinued. Users are effectively locked into using web interface which requires context-switching.