React, Flux, GraphQL, Hack, HHVM...? All of this and more!
Angular 2 was a gigantic effort that rewrote the most popular front end framework. This was a big risk as the (still) continuously increasing developer base of Angular 1.x could abandon ship as their skills were rendered useless.
However the architectural improvements seem well worth the big change and the new version is a contemporary full stack framework. With wide adoption inside of Google it is guaranteed to have years, perhaps even a decade worths of life in it.
Sporting semantic versioning the new framework can also move forward at a steady and predictable manner. This is a common pattern in the CMS world, where big releases have given way to quick release cycles with minor version upgrades.
Compared to React, Angular 2 is a different beast altogether as it provides all the bits and pieces from routing to HTTP connectivity in one clean package. Written in TypeScript it's a robust platform that can be used to write enterprise scale front end applications.
Compared to React's minimal and somewhat fragmented development practises a full stack framework, like Angular 2, provides a consistent developer experience for all projects. You could think of React like Android and Angular iOS. Both have their pro's and con's.
Angular 2 is definitely worth the time investment to look into, even for React developers: