For me it doesn't work. Generated tests fail to run or they fail.
I work in large C# codebases and in each file I have lots of injected dependencies. I have one public method which can call lots of private methods in the same class.
AI either doesn't properly mock the dependencies, either ignores what happens in the private methods.
If I take a lot of time guiding it where to look, it can generate unit tests that pass. But it takes longer than if I write the unit tests myself.