I'm super glad that Stack Exchange finally made mobile apps -- the notification service is really useful and keeps me on the ball. After quite a few months of use, I'm noticing two main pain points.
The first is that there's no autocorrect when entering comments. The keyboard suggests the correct word, but when I hit space it leaves the misspelled word, whereas in other apps (and even other parts of this app, like writing an answer) the typo would be automatically corrected:
My next feedback is about the text size. It's too small:
I have to hold my phone to my face to read comfortably, whereas I can read Twitter, the news, and websites just fine without burying my face in my phone.
(Before you flag as duplicate, consider that unlike those other questions about font size, mine is still unique because I'm also providing feedback about the autocorrect issue.)
Most reading and writing apps let you adjust the font size independently of the system font because the reader may spend hours (or at least several minutes) absorbed into the content presented by the app. They also account for screen size, margins along the edges (whitespace lends to legibility), and pixel density of devices. I'm talking about apps like Pocket and Google Play Books, both of which are very comfortable for reading in.
That other question suggests pinch-and-zoom. I don't even want that -- the text should just wrap itself to fit on the screen. Take a look at other reading apps to see what I mean.
Akin to the very small font size are the vote buttons, which are smaller than the size of my pinkie fingernail. Even the UI elements along the top and bottom are a little bigger than that. (On my tablet, the font sizes are even more disproportionately small.)
Please consider this perspective when working on updates to the Android app. I believe whitespace, font size, and spelling correction are important in making Stack Exchange a top-tier reading & writing app.