[thrtythreeforty]

If you want to be reductionist, everything is a feature. But if an app is missing something so basic as to impact usability, I might consider it a bug. It's a matter of opinion where the line is, of course.

Uncontroversial example: a calculator app that doesn't have a divide key. Technically, yes, it's a separate feature from the multiply key, but it's so basic, so expected, that its absence is a bug.

From the above list, I consider "No easy way to do and restore backups on Android and impossible to do backups on their PC client" a bug, or at least a frustrating omission by design.