- Invite people to share document
- People can highlight text and post a comment or suggest an edit in a sidebar comment stream
- Other reply to comments
- Revise means editing the document as opposed to annotations
- Permissions (Comment, Revise or both)
- Email notification, or check the website (new comments are in bold)
- Save a document back to your desktop
The blog also has a nice scenario run down.
The only thing I’m not sure about is when you submit a revision, is there a version history, and if there is, can you see the changes that make it different to the previous version.