Do you use service workers for your web app?

I'm just curious to understand if anyone is using service workers for their web app in production and if so, what use cases does it solve particularly well.

More specifically, in terms of caching, apart from working offline how is it different from browser/CDN cache? What if your service worker itself is cached for sometime and you want to rollout an update? What are the best practices? How has your experience been maintaining service worker on a production app? What about security?

I know notifications can be done, server push with HTTP/2 etc. But which kind of web apps can make the best use of service workers and which ones shouldn't implement it?