Doc secrets is certainly an interesting add-on with potential. It's a fairly simple idea and seemed to work well with minimal issues. Here's what I like best:
- With the add-on you have the ability (as the creator) to block others from seeing certain content on your Doc. You may still want collaborators, which is great, but the add-on emables you to keep certain parts of a Doc private.
- It's responsive to your movement. If I move the cursor to "protected" locations, it brings this to your attention. Nice idea.
- You have the freedom to reveal certain secrets to certain collaborators.
- Easy to get going, minimal learning curve.
- Extremely simple design - so simple that some may find the colors problematic.
My biggest concern was there was no "safety net." This is not backed through your Google account anyhow, so if someone forgets the code/password, that sensitive/secret info is gone forever (so it seems). A security question feature would be nice. Another idea would be to give users options with regards to the color coding.