No good Rated 1 out of 5 stars
To add to what freakQNC said:
When I had this addon/extension installed - often when I viewed a web page that contained a hyperlink for a pdf and I clicked on the hyperlink, a new tab opened in Firefox but the pdf was not displayed. When I removed this addon/extension, I then had the option (because I had DownThemAll! addon/extension installed) of opening the pdf in Firefox or saving the pdf.