Compared to Hugo (which is what I was using until then), it has:

- the mentioned Sass compilation

- a much better template engine (I'm a bit biased there since I also wrote it)

- assets colocations: keep images etc next to the post

I also find it much easier to use than Hugo but I wrote Gutenberg for my own usecase so this point would need external validation.

I wrote a bit about the motivation when I released the initial version on my blog: https://vincent.is/announcing-gutenberg/ but I agree it should be better communicated on the landing page.

Rust is an implementation detail: it could have been done in any language compiling to a binary, I just picked the one I prefer.