I found it quick to understand the ideas behind React, but it was a lot more difficult to understand how to apply that to practical problems and to 'think' in React.

React.js By Example [http://reactkungfu.com/react-by-example/] was enormously helpful in showing how to structure various different real-world apps. So if you find yourself beyond the basic CommentBox examples, but not sure how to build your own components then this might help.