I read some description ob what that is and it looks like checking out different commits (via bisection) until you figure out where in the history some change happened. Is there some other benefit I am missing?
It's not about finding a particular change, it's about which change broke something.
In the best cases, it's totally automatic. You know that it worked at commit A and is broken by commit Z. So it checks out commit M and runs the tests. If they succeed, then it broke somewhere between M and Z. If they fail, then it broke somewhere between A and M. So it checks out either H or S, depending, and repeat.
It's not always that easy, especially when your tests and environment are complicated. There's often manual intervention, which is tedious. Still, log2 N steps is often manageable, especially if the computer is taking care of the tracking for you.
It automatically does a binary search, and you can use it completely automatically if you can write a script that determines if the bug was present.
The other day I used it to write a good bug report. I first used it to find the earliest commit I could compile on my machine, then I used it to find the commit where a certain command would fail.
