Foxit Reader can open various documents at once in different tabs, and add bookmarks, so you can quickly go back to a certain section of the text. Not only that, but it supports almost all same files as Adobe's proprietary software, except for PDX format.
Foxit Reader also has a media player that can play files that are embedded in some PDFs, such as Ebooks. Not only that, but this app includes a magnifying glass to enlarge parts of the page, an automatic scroll feature, and the ability to add notes, underline text, and even draw on PDFs.
As well as editing existing PDFs, Foxit Reader can create new PDFs from compatible text documents or copied text. Foxit Reader also has integrated Twitter, Facebook, Evernote, and Microsoft Sharepoint tools, and even collaborative features, such as version management, and the ability for various users to add notes.