What I love about Docs in the 3.0 version is that I can work on a document without any distractions. The interface is minimal and clean. (I'd even opt not to have the search bar visible at the top, but it is easy enough to ignore.)

With 4.0, I see the doc, the sidebar / navbar on the left, the pinned docs at the bottom, and more. This makes it challenging to focus on what I am working on within a document. I now have four or five visual references I have to mentally block out in order to focus.

It would be helpful to have the option to show the items outside of the document. Some people may want them for quick access, but others may find them distracting. I like the minimal interface for 3.0 docs.