Did you watch the video? They're taking a genuinely new approach here. It's not "lowest common denominator" like Xamarin, Qt, etc, and it's also not a WebView like Atom or Ionic (Cordova).
It's actual native components, with the intent that you "learn once, write everywhere" rather than try to jam iOS and Android into the same codebase.
Re:A Deep Dive on React Native [video]
by danabramov on Friday January 30, 2015 @07:38AM
(#8971701)
To be fair, Xamarin isn't "lowest common denominator" either.
It's all native and even with xplat Xamarin.Forms you can customize code for each platform.
It's like how we never got a fix for making cross platform applications. And regardless how much people wants the new way of doing things to work, the results speak for themselves. Atom, the editor, can't even handle window re-sizing smoothly.