Doro PDF Writer is a very simple software to convert files to PDF. It works as a virtual printer and offers only a limited number of options.
You can add some metadata information such as author name, title and encrypt the PDF with a password. Also, it allows to restrict the editing actions or printing.
There are faster free PDF printers.
Is not very weak at preserving a small file size, but there are better programs to do it.
This program doesn't excel at anything, is good to use if you don't have other requirements than a simple generator from one format to PDF.