This module is not installable by cpan, which complains about missing files. I suspect there's nothing missing, but that it is improperly packaged. I also suspect this module is largely superseded by the Carp module's confess() subroutine.
Yes, the WMI interface is slow and a bit leaky. The NT variant is faster, more stable, and doesn't leak, and is recommended for daemon applications, or where speed is critical. I withhold ratings since I'm the author.