- There is a way to separate component's state from component's properties. Apparently it existed even before this update; but the docs weren't very clear on that. The docs were rather niggardly in the information they supplied, I must say.
- There is a proposal for a browser api to encapsulate the declarations of custom elements within their hosts. Which is clumsier than what we get with frameworks, but at least makes web components more suitable for large codebases.
- There is a convenient way to share common functionality between components.
- There is support of server-side rendering.
All in all, pretty uplifting stuff. But of course I am now entrenched in React at work.