When comparing Bitbucket's bug tracker vs JIRA, the Slant community recommends JIRA for most people. In the question“What are the best issue tracking tools for mid sized software companies?” JIRA is ranked 4th while Bitbucket's bug tracker is ranked 10th. The most important reason people chose JIRA is:
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.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free unlimited private repositories for small teams
Bitbucket offers unlimited private repositories for free, as long as the number of members in a team is not larger than 5. BitBucket does not use GitHub's pricing plan, instead of charging users for each private repo, it charges teams per number of team members. It is free for up to 5 people.
Pro Supports both Mercurial and Git
Has full support for both Mercurial and Git VCS.
Pro Native application for both Mac and Windows
Atlassian, the company behind BitBucket is also behind SourceTree, a free application for Windows and Mac wich works as a client for both Git and Mercurial which can be connected to BitBucket and other code hosting services.
Pro Multiple authentication methods
BitBucket supports GitHub, Twitter, Facebook, OpenID, Google and even GitHub authentication.
Pro Lots of 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 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.
Pro Very cheap for small teams
Pro Supports version-focused work-flows
JIRA is not a plain long list of tickets, but can be configured to be version-focused, so planning and understanding the progress in a software project becomes clear.
Pro Great reporting tools
Jira offers amazingly powerful reporting tools like activity stream, different graphs of opened and closed issues over time etc...
Cons
Con The UI seems old and not very polished
While GitHub's UI is extremely simple to understand and very polished, BitBucket lacks a bit on this category. With a design that seems old and not as pleasant to look at.
Con Only 5 users are free
5 users free: Unlimited private repos, Dedicated support, Code reviews, Custom domains, JIRA integration, REST API.
Con Integration with other tools is not as good as github
Most of the 3rd party tools ( bug trackers, CI servers, chat servers, etc) always integrate with GitHub first, and either don't integrate with Bitbucket at all or do sub par job in it. For example there are 3 separate projects to allow building and verifying pull request submissions on Jenkins CI server and there is only one viable one for BitBucket and that one is really buggy and lacking many features.
The only exception to this rule is Atlassian products like Jira.
Con New releases often change the GUI largely
Sometimes the usage becomes worse, e.g. when creating a new ticket, you need to click the notification to keep it on the display.
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.