If nothing else, git bisect allows any user[0] to find when a bug they are experiencing was introduced to the codebase.

They do not need to be familiar with the code, the language, that module, the library, the developer or have anything more than the knowledge of how to check out/bisect the code base, and how to reproduce the bug.

For this it is an invaluable tool, and I can't count the number of times on the git mailing list that a simple bug report has allowed a developer to quickly locate the exact commit an issue was introduced and investigate further. A recent example is at [1].

[0] Here a user refers to any of 'technical user', 'developer', 'maintainer', 'original author', or really anyone who has the ability to check out the repository.

[1] http://thread.gmane.org/gmane.comp.version-control.git/21504...