As part of the roadmap unveiled at WordCamp EU earlier this year, WordPress.com has started rolling out Gutenberg to a subset of users.
According to a WordPress.com Happiness Engineer , the team is testing the implementation to determine the best way and time to enable it. Users will not be able to use Gutenberg unless their theme is updated to support blocks and the various alignment options.
Theme Wranglers are already in the process of adding support to WordPress.com’s nearly 100 free themes.
A quick search of the WordPress.com support forums for Gutenberg provides some insight into what users think about the new editor. For example, this user provided feedback on the use of so many icons without displaying their textual equivalent.
For now, Gutenberg is opt-in but eventually will be opt-out. Once Gutenberg is made available to a wider audience, support documents and official blog posts will be published to inform users about the new editor.