React Router has been iterating towards better APIs for advanced use cases (server-side rendering, code splitting, relay (and other lib) integration, etc). Having used it in projects spanning the above use cases, the evolution of the API has been welcome change.

I'm also happy to see codemods and other AST manipulations (such as babel plugins) gaining popularity. Similar to eslint's --fix, codemods are making repetitive changes easier across large codebases.