Sharing a notebook is very convenient. What I would also like to see is the possibility to write-protect the shared notebook. I work at a school and share my notes with the students by exporting them as PDFs and uploading them to our learning management system. I have to do this over and over again after each new lesson. It would be easier for me to share the Goodnotes notebook directly as a link (all students use GoodNotes on the iPad) without students having the ability to change anything in my document/notebook.