The language itself is great, it has basic syntax of “high level” programming languages, and also allows many “freedom” styles as well as “magic” . But I would say that the best thing of JS is that from the “magic” of the languages, there are great developers who create amazing “libraries”, or “utilities/frameworks” if you prefer.
One of the masterpieces is jQuery. Another is NodeJs. And for “next-generation” frameworks, there are quite a few ones which are pretty potential and awesome to create full front-end for web applications (as well as other applications – JS can model/emulate them all!).
I’m a bit slow to adopt these new libraries, but from my quick looks it seems AngularJS is very well-rounded: cool, helpful, mature and easy to learn.