I've been using Zotero as my "book" organizer. I have all my epubs, pdfs, everything there. Since version 7 I think you can read PDFs within Zotero, and I love it. I keep custom labels so I easily search for stuff. The only feature I don't use is everything about citation (funny enough). Before Zotero I had everything in file system directories, but I wanted the feeling of having one place (one app) where I could see all my books by category, by read/no-read, etc.
Having said this, I will probably wait a bit before upgrading to V8 (since I use it everyday, so I wouldn't like to face bugs and the like)
Having said this, I will probably wait a bit before upgrading to V8 (since I use it everyday, so I wouldn't like to face bugs and the like)