A few thoughts:

When on the comments page, I'd expect tapping the title to take me to the article, but it doesn't.

The child comment touch target is all the way to the far right, which is at the edge of the touch region on the new larger phones. Feels a bit awkward. Maybe make the entire comment the touch target for that?

Not a fan of the big black back arrow. I know it goes away, but as you scroll, it is right where you want to start reading, and feels a bit distracting. Maybe just tone it down a bit?

There's a little bit of stuttering as you scroll, which is surprising for a text list. I'm guessing it's a bug rather than actual performance issues.