I really love goodreader. Its an excellent app. My issue has been customer service and troubleshooting. I have been working on an invalid server response error for sometime now but nothing is working. The documentation is of no use. The unofficial discussion groups have no answers and the official response has been one automated email saying they have received my email. So waiting for now without syncing.
Update: issues with syncing to Onedrive which had a 100 MB upload limit for third party apps. But according to Onedrive blog they have changed that restriction a few months ago but goodreader has not updated. So I cant use goodreader for my textbooks now.
Lonemavericks about GoodReader PDF Editor & Viewer, v4.12.1