In my opinion, whitespace is fine when it's used to separate functionally distinct UI elements. What I find most aggravating is when white space is used to pad

In my opinion, whitespace is fine when it's used to separate functionally distinct UI elements. What I find most aggravating is when white space is used to pad out lists of items. For example, I got in the habit of using Google Keep to keep track of things like checklists and shopping lists on my phone. Then a few months ago, they updated the app so that every line of text has 2 lines' worth of whitespace above and below it, and now I can only fit half as much of any given list on my screen without scrolling. (And of course, unlike a web site, there's no way to override the styling of an Android app.) Every time I see somebody making their UI worse in this way, I remember all the previous times I've seen it happen, and I get slightly more irritated than the last time.