> It doesn't generate good tests by default though.

I agree with this.

I've found I need a whole separate cycle of test writing to get proper (in both scope and accuracy) coverage.

It does help tremendously with all the boilerplate of tests, and it seems to be quite good at setting up numerous tests for all combinations of variables. It does have to be done explicitly, though.

And you do need to mind when a test fails whether it fixes the test or the code.