I don't like this module a lot for two reasons. You can't have a signature for an anonymous sub, and bug reports are being ignored for months.
Allowing signatures, i.e. the specifics of the parameters being passed to a subroutine, is a welcome addition to perl to make it more readable. To have this functionality without using the black magic of Source Filters is even better.
Use this module, and its brother Method::Signatures, if you want cleaner, more readable code.