Fast paced, iterative, development is fine. It's his bold statelents like "will significantly upgrade the publishing ability" that I feel are completely wrong. The idea behind Gutenberg is fine, the implementaiton is not.

Attempting to write anything in the editor is still a hassle, and is far harder than in the classic editor. The current Gutenberg will not be a significant upgrade as Matt states, but a huge step backwards on every single front.