This is the leading PDF viewing app in the App Store, but its really not fit for purpose unless your purpose is an extremely complex setup involving the handling of hundreds of PDFs, and vast amounts of Internet research. You also have to be a former Windows user, or a senior citizen to appreciate the ridiculous old-school interface of menus, buttons and obtuse settings.
The app designers make the classic mistake of including everything *including* the kitchen sink in the App leading to possibly the worst, and most cluttered UI I have ever seen. There is more space devoted to the clunky UI than there is to your files.
Jeremy Bee about GoodReader PDF Editor & Viewer, v4.12.1