I'm looking forward to trying this out. Having written Ember, Angular, and React apps now, I feel like they are all getting closer, but a lot of rough edges still exist.
Ember: interesting framework, but all too often, you would hear a team mate say "wait, why is that working, it shouldn't be?" Mixed with equal parts "logically, that SHOULD work, what am I missing?"
React: I love the component focus, and redux is pretty slick. However, the insistence on using JavaScript in lieu of helpful abstractions that clean up the code for easier maintainability, is frustrating. The whole point of JSX is syntactical sugar, but the team went with half measures. You also end up with a lot more plumbing code than the other two. Sure, I can reuse some of these components, but in truth, most of your components will be single use.
Angular 1: by far the easiest and most intuitive. Enough magic to make setup and a basic app easy, but not so much magic that you can't figure out why something is working. However, the more complex an app, the less Angular 1 serves. And you really need to use directives as a component, and follow a more react pattern, or you're going to have a bad time. Also, the dependency injection is a nice thought for simple directives, but when you're done, you'll very likely have so many dependencies being injected that unit testing becomes burdensome. And if it's burdensome, it won't be done as much as needed.
All that being said, if your app is primarily collecting data through forms, you can't beat angular. If it's highly dynamic, and you want a more native feel to your app, react is the clear winner. Ember is a neat, but I won't be using it again.
Angular 2 doesn't fix all of my complaints, but it's getting closer.