My pet peeves: No dark mode, sorely lacking for me for reading in the dark, then there is no indication at all that you've got replies (at least a tiny number next to threads perhaps?) and the up/downvote buttons are too small to reliably tap on mobile. Oh, and enumeration support would be fantastic, the workarounds tend to be hard to read.
Other than that, I think it's delightfully ugly and lightweight.
I can't seem to find Harmonic in the iOS App Store, is it Android-only?
Also, HN apps tend to make it harder to send interesting things to Roam or the laptop or Safari's reading list, the website makes that really convenient.
Other than that, I think it's delightfully ugly and lightweight.