I'm been using this for about a month as a replacement to Test::MockObject->fake_module. The advatange of this module is its ability to undo package mocking. This is important in making sure my tests don't interact.
It could do with more semantic sugar like Test::MockObject in order to test if mocks were called, how they were called, etc.
I would recommend people look elsewhere for an inside-out object package. The POD of this module refers to a few alternatives. There are lots of open bugs for this module and there doesn't seem to be much activity fixing them.