use'ing it in your test file will capture STDERR and add a test that fails if any warnings were emitted in your tests or code-under-test.
I've been using it for years and I've never had a problem with it.
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.
So far so good. It work and the semantics are reasonable. I've been playing around with it for some weeks but haven't used it in a production project yet.
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.
I've been using this for over a year and its been very helpful building rpms for redhat distrubutions.