Here are the things I had the most trouble with in the beginning:

- Externals. I still have trouble wrapping my head around this directive.

- Multiple output paths for multiple entry points (it wasn't intuitive to make the entry point key a relative path and I had to discover this method on stack overflow).

To be fair, a proper set of documentation for webpack would be a several hundred page book.

Edit: I see my second point still isn't mentioned anywhere in the old or new docs. Specifically:

  const ExtractCSS = new ExtractTextPlugin('[name].css');
  ...
  entry: {
    ['./app/bundle']: './source/app/index.js',
    ['./admin/bundle']: './source/admin/index.js'
  },
  output: {
    path: './build/',
    filename: '[name].js'
  }
  ...

would create:

  build/
    app/
      bundle.js
      bundle.css
    admin/
      bundle.js
      bundle.css