Hmm. I can't think of any time I've thought the app was really missing something, or didn't work. In fact, I always thought the app was pretty smooth and "just worked".

By comparison, several years ago, I was regularly streaming Netflix content without any trouble. One day I streamed a show on the HBO app on mobile data and it ate up almost all of my month's data usage. I guess it's behind the scenes work, and not so exciting, to e.g. stream a smaller resolution for a mobile phone, but in moments like that you realise there are a substantial amount of things to think about when making such an app.