Can you give some details about how things blow up in complexity? I've not built a complex app in React yet, so I'm looking for things to watch out for.
sure it starts with decoupling data describing the application state from DOM itself the way I understand it. So you write JSX which is a novel idea in itself and claims to 'bring html to js not like angularjs that brings js to html with annotations' but then you end up fiddling, chasing down which hierarchy of class that gets quite big over time.
Unless you were in a large design agency it doesn't make sense to add the abstraction overhead for majority of today's single page apps can be pulled off with jquery libraries from unheap.com
In a typical jQuery/Backbone kind of app, you've got some data in something like Backbone models and you've got state stored in the DOM. Keeping those two in sync bring complexity in. The React model is simpler (in the non-intertwined sense... see Simple Made Easy[1]) in that you have data in one place, a function that transforms the data to UI and the browser DOM is managed automatically from that.