What does it give you above other frameworks, specifically Angular?
I wrote a little bit about my experiences here:
http://benalpert.com/2013/06/09/using-react-to-speed-up-khan...
In short, it's simple (very little to learn) and very fast. One other big thing I love is that it encourages building reusable and composable components. Angular has a lot of the same structure, but if you end up building directives then you have to drop down to manual DOM manipulation again if you want speed.
Happy to answer questions.