Unsure whether this has already been submitted, but I noticed that when configuring a file-level backup it is unclear whether or not there are any unselected folders further down a directory tree, without having to manually inspect each folder.
For example, look at this selection ..

You might be inclined to think that all the above folders and its subfolders are selected for backup. But this is not the case. When I drill down...

... you can see a previously unselected folder. This can be dangerous as you may have things not getting backed up when you inadvertently think they are.
Each parent of an unselected folder should have its check box different, such as a greyed-out tick, so one knows that there are unselected items beneath it somewhere.