Too Long; Didn't Read
Gatsby is good for react portfolio sites, but worse than NextJs for web apps and much slower to work and more of a hassle than Web Builders/CMS for brochure/primarily static sites. The framework was initially described as a static site builder for React, but this description has been retracted by the developers. The site is still usable with JavaScript disabled (unlike with vanilla React) and the client does not have to do the heavy lifting of assembling the site with JavaScript. Data fetching is easy, but REST support is poor, and there are still many data sources that do not support REST out of the box.