Gutenberg is the default WordPress editor since the latest WordPress version 5. WordPress has completely re-imagined the way we create posts and pages. We must say it is one of the biggest updates since WordPress released. With Gutenberg, creating a website is a lot easier. It is based on blocks and each block represents a type of content. Essentially Gutenberg is a mini version of WordPress builder plugins like element.
As from our experience, Gutenberg is not so publishers and bloggers, it is still developing hopefully it will be flexible in the near future. If you were using a classic editor you might find it is a bit of hassle to work with it and there is some learning curve involved. You might also notice some great Gutenberg add on plugins are also released to powerup the editor.