x0 now accepts a folder of components as the entry argument
Automatic routing based on filename
Dev server uses webpack-serve under the hood
Uses mini-html-webpack-plugin
Default HTML head contents for UTF-8 charset and viewport meta tag
Minimal base CSS styling
Rendering the <head> in the component is no longer supported
Webpack is used both for the client and static rendering, enabling webpack features in getInitialProps
Support for babel-plugin-macros
Default props can no longer be passed through the package.json config
The routes array in package.json is no longer supported
Adding react-router is no longer necessary
Removes react-loadable support
Proxy option is no longer supported, but can be configured with a custom webpack config
Automatically looks for a webpack.config.js file in the directory
The --config flag has been renamed to --webpack
Automatic support for styled-components
Automatic support for emotion
Custom HTML template option
Supports custom App component to wrap all routes
Support for JSX file format
Support for MDX file format

A directory should be passed to the x0 command, instead of a single file
React router is not necessary for routing
The routes option is no longer supported
HTML head contents should be removed from components
Viewport and charset meta tags are included by default
Use the custom template option or head options to populate HTML head contents
Default props set in options should be added to the components
Custom usage of react-loadable will require additional setup
The --config flag should be renamed to --webpack
The proxy option is no longer supported
The cssLibrary option is no longer required
Support for automatic static rendering with glamor, glamorous, and fela is no longer supported
The getInitialProps method's pathname argument has be renamed to path
The getInitialProps method only receives the path argument, all other arguments are deprecated