I co-authored this one, so I'm avoiding a formal rating.
When it was written in 2005, it provided a much nicer interface to HTML::FillInForm. However, those warts were all addressed in the HTML::FillInForm 2.00 release. The remaining value this adds to CGI::Application is defaulting to $self->query for the data source, and automatically ignoring "rm" as a form field. If those features aren't important to you, it would be simpler to use HTML::FillInForm 2.x directly.