[CuriouslyC]

Angular was nice because two way data binding greatly simplified a lot of user-interface management code, and dependency injection made it easier to cleanly factor your code. Unfortunately, the boilerplate involved in creating directives tends to result in monolithic html templates that do way too much (and are hard to maintain), and the digest cycle/dirty checking ends up causing a lot of issues when things get complicated.

React makes it easy to create small components, encouraging maintainable, reusable software. On the flip side, passing data around in your application is a lot of work, and even the best current solution (unidirectional data flow with something like Redux) is very oblique and involves significant boilerplate.

In my opinion the React/Redux model is pretty good, and the libraries are well designed, there is just a need for a good framework to deal with the indirection involved in unidirectional state flow. I'm currently working on something in this space, it just needs some additional battle-testing so I can settle on the interface and work out all the kinks.