Besides the visual design, I've been thinking about the tech part of it. There's so many bits shifting, morphing and having state, that it sounds antithetical to what a UI is supposed to be: a consistent and unnoticeable tool to interact with software. I do like some of the things they do to free up screen space, but having components being to programmatically complex is bound to cause issues. Besides having your presentation desync with your data, your UI now has opportunities to desync with itself...