Easy to use, customizable, syncs with iOS version

Very easy to use - simple, straightforward interface doesn’t get in the way of your work

Highly customizable - you can tweak keyboard shortcuts so that the program works the way you think, rather than having to change your workflow to suit the program.

Syncs with iOS version - this is a great feature to have, but unfortunately uses iCloud so is sometimes delayed… would be better if it used dropbox or another service.

In addition to outlining, I find the app to be PERFECT for creating packing lists, due to support for checkboxes

snoop_z about Cloud Outliner - Outline Maker, v2.1