The only complain I have about it is related to use it to read UTF-8 INI files with BOM: the module does not seem to be able to read those files, even with some different attempts of passing encoding argument to read(). The module must remove the BOM before running validations in the INI format (see String::BOM).
Documentation could also see some improvements regarding encoding options.
I really like the concept of the ::Tiny modules and use this one all the time. It is ideal for small and/or new projects where the temptation is often to just stick the configuration in a hash at the top of your program. Using this module makes keeping it separate from my code trivial, and with minimum overhead.