Negative. This is just a tool for creating Metro apps and it has existed since Windows 8 came out. People are talking about it now because Microsoft just open sourced it.

How does it compare with AngularJS? There might be some overlap but it is not a competitor. In fact, Microsoft uses AngularJS frequently on their sessions, documents, templates, etc.

http://channel9.msdn.com/events/build/2014?sort=sequential&d...

Edit: It seems like Microsoft is transforming WinJS into a general purpose JS library.

https://github.com/winjs/winjs/wiki/Roadmap#the-present