Great post. I recently started a project using reactjs, and I have nothing but good things to say. The unidirectional data flow, the declarative nature, and the virtual DOM makes it powerful and very easy to like.

The best resource is to follow the tutorial (link below). The tutorial explains everything you may have a question about when comparing it to Backbone, Angular, or Ember.

http://facebook.github.io/react/docs/tutorial.html

I also found the IRC channel to be very, very helpful.

The only downside is that you still have to rely on other tools to make a true SPA like routing.