I had no trouble at all installing this module. It works as advertised. The only thing I would improve: It would be nice if there was a script included that takes a maildir as its argument and list all duplicate emails - I think this is a common usecase for this module. Of course it ist trivial to implement this, but hosting such a script as a standalone application would bring more people to use it (an Perl) for the task.
I'm not sure what Mixer's complaint is when he says, "Awful module, doesn't work." He hasn't filed any bug reports of communicated with me about it in any way--but this module has more than 170 passing tests on record, and only three failures. Two of them seem to be specific to Windows/Cygwin, and I'll be looking into them.
If there are any problems with the module, or features you need, please open a ticket, since I am actively maintaining this module. If you're having trouble using it, contact me and I'll both help, and update the documentation as appropriate.