The improvement is good, really good. But there's something that's hard to understand. All these features is to improve the user experience with Gutenberg. But why don't they think about developers. If for some reasons a block can't render itself, an error is shown in browser console and the whole block is lost. You can't recover it. That's not the best option to catch an exception. Everybody talk about this way of showing issues, but nobody seems to care about it.

More than it, the DOM structure in Gutenberg is different from what is rendered on frontend. That's a problem because as a developer you have to maintain two structures that look the same, and the pixel perfect between the two is hard to.