I've built three web apps using Cesium, so I'm familiar with some of its complexities. The first uses GWT/SmartGWT, the second uses Backbone, and the third uses React+Redux+Webpack. Of the three, I'm the happiest with the React+Redux one so far.

I'm actually hoping to write a blog post in the next few weeks discussing how to use Cesium with React+Webpack: basic setup, using React to render Cesium primitives, and then advanced Webpack setup for code splitting.