You can just choose a story on the sidebar and the corresponding website will load inside the app. No more needing to open an endless amount of tabs for HN and you can switch to the comments using a keyboard shortcut.
The app offers an optional split screen mode to view the website and the comments next to each other. It's an awesome way to read HN if your screen is large enough.
By pressing a keyboard shortcut you can switch to viewing the comments right inside the app. They were prefetched while you read the article. There are also keyboard shortcuts to navigate through the comments and you can fold comments.
You can go through different story lists, just like on HN. For example you can go through all the latest "Show HN" or "Ask HN" posts. Unlike other apps this app gets the details right, like directly showing the comments for "Ask HN" posts, instead of rendering an empty website.
New articles are automatically loaded if you scrolled down far enough on the "Top Stories" list
You can easily navigate the app using Vim like keyboard shortcuts, there's a complete list here or just press h in the app
You can view website and comments next to each other or cycle through the different display modes using the shortcut l
Some websites have a terrible reading experience but you can use Readability inside the app to fix that
You can navigate the comments using keyboard shortcuts and fold them which makes a great comment reading experience
Reading PDFs inside the app is no problem, it's automatically detected when to display a PDF reader
Read stories are marked as such, just like in the browser
Things that other HN apps usually forget are included, e.g. viewing HN polls right inside the app
It's open source and on GitHub, you can contribute to it or just change it however you like :)