If you're looking for input, look to the store comments. The number one comment is also my biggest complaint -- I want an option to open links in my external browser not your (limited) integrated browser. At minimum, improve CSS handling in the integrated browser .. support at least bold and italic text. Photo captions, quotes, etc. end up indistinguishable from article content because everything is rendered in the same style.
A smaller, though annoying issue is that waking the app from the background restarts it. Say I'm reading an article, get a call or otherwise background the app with that article still open. If I try to come back to it more than a few seconds later, the app restarts and I'm back to the article list.
And a minor bug, I've selected the blue theme. When the app starts, it shows the UI in orange (default) for a moment then switches to blue.
BTW, in your intro here you say the app is missing collapsible comments, but they are in the app and even in your screenshots on the store. This is a great feature and one I use regularly.
If you add the external browser option and fix the wake-from-background issue, I'd happily pay a buck or two for the app (or a pro version).