While it may be that the user interface of the fireshot add-on could be improved and that options for fine tuning of the results could be offered, this is the only product of its kind that works. Period.
For years I have been trying all available Pdf add-ons, and at best they just truncate pages or render them in a wrong landscape format, but more often than not the resulting document contains just garbage with a destroyed layout, missing images etc.
So actually if you want to save a web page to an image or a document this is the only choice you have.