The downvoters just amaze me :) The front page of this addon explicitly states that it sends the entire content of your web pages over the internet in order to create a PDF, and still some people complain about privacy issues, athors lying about something or possible scam.
If you are afraid that the websites you visit are of any interest to whoever you think might look through them - just don't use this addon. As simple as that.
For me it works like a charm. It gets the job done, and that's the most important thing for me.