Getting started with React, React/Flux from an AngularJS Perspective, and the case for Flux
If you're new to React this is also a great article to check out. Ryan walks through everything from JSX and the virtual DOM to state and props + more.
If Dan writes something, you should probably take some time to read it. He produces some really good material. In this article Dan talks about when you should, and shouldn't use Flux in your projects and expounds on the dangers of dogmas in upcoming technologies.
This one slipped by a lot of people with the announcement of React Native. Reapp lets you build hybrid mobile apps with React, Webpack, and ES6 - today.