This module is virtually undocumented. It's probably a great module and does everything, but with documentation this minimal, I'm left with the options of either (a) reading the source code and the Apple TrueType manuals and trying to work out what this does (b) reading the Apple TrueType manuals and just writing the bits of code which I need to do the jobs I want to do. For me, (b) is probably going to take less time and be less frustrating.
The core documentation, Font::TTF::Manual, really tells me next to nothing about what the package does, instead it describes architectural decisions made when designing the module. There are scraps of information in each of the submodule documents, but it's just not enough to get started.
Which is a shame, since the module looks like it's really comprehensive. If the authors would like people to use this module they should try to rewrite the documentation from the user's perspective.