Google does rank the PDF pages, however it is very useful to input all those optional fields under File -> Properties to help placement, so you need to use Acrobat or a full fledged PDF editor rather than just a PDF writer.

For a product specific search term with 453k results, our PDF page ranks 14th on Google and the HTML is listed underneath it. It might rank higher if we had a better page title..

The quality of copy etc I believe still applies, along with the basics of keywords.