I don't think this is a very good example of a demo angular app. Hackernews isn't an app, it's a site. It works so well simply because it is such a simple site. If you're going to build it in angular, might I suggest you add some functional benefit to using the tool.
The main benefit seems to be that it's based on a Firebase backend and updates in realtime.
I agree. From what I could see, it didn't look like it offered any extra or special functionality. I had expected it to do more dynamic loading of things like comments (like a nice transition over to a comments display or something similar).
The API has comment support, I'd love to see that. However as of now it's read-only. To make it read-write you'd need to fully integrate firebase. This is just a firebase mirror of the data. Discussion forums with threaded comments don't really make sense for realtime updates. I don't think they have Windowing functions either, so you'd get only the latest x comments or the best x comments, and you couldn't "get more".
I'm behind a corporate firewall that (for some reason) blocks firebaseio.com - with the result that I get a blank page.
It would be worth at least letting users know why they don't get any data displayed.
Yep, looks about right for Angular: flashy but not-particularly-useful functionality (dynamic real time updates) while sacrificing basic web usability (blinky-blink loads, strange back button behavior, etc.)