I've been using the Gutenberg plugin on a WordPress test site since January of this year (2018). You might think that makes me an experienced user, but the fact is that I constantly feel that I am not exploring all the features.
Just yesterday I learned that it is possible to see the layout structure or 'document outline' at it is called, of a page or post. I simply never noticed it before.
The document outline is a way to see how you have organized your content using headers. And you can jump to different parts of the content by clicking on any of the headers, rather than having to scroll to the section of the post you want to work on.
I can see this being useful when you are working on a piece of long-form writing and you have got a page or post with lots of text.
Here is a snapshot of the layout structure of a post I wrote yesterday after finding out about this view. I have pointed out the little 'i' in a circle - and when you click that it shows the rectangle of information about the document outline superimposed over the post or page.
On a separate but related topic - one thing I already knew about was how to move blocks (paragraphs of text or images or whatever) higher up or lower down the flow of the post or page, and how to insert new blocks (paragraphs of text or images or whatever).