The one annnoying thing is that, while they generally work well without the app, there's one button that can function as either:

- activate Google Assistant or Siri

- disable noise cancelling

Given that I don't have the app, I can't use the former anyway. However, to set up the button for the latter functionality, I have to use the app.

In other words, I can't turn off noise cancelling, and have a useless button on my headphones.