Macaroon is a macro-based "action bar" addon. Up until Macaroon, even considering Trinity Bars, all bar addons were action ID based (at least "out-of-the-box" they were). Macaroon aims to expand beyond the limitations of the action ID system through maximum use of the macro-based button which was introduced in WoW 2.x.
Macaroon is designed to be many things to many users. It can stand on its own as a full-fledged bar addon. Or it can even run side-by-side with other bar addons. It can be an addon for keybinders or even clickers. The whole of the addon is designed to be as feature rich as a user may need, without needing to "fuss" with options one does not care about.
Macaroon is centered around the WoW macro. However, you do not need to know how to write a single WoW macro to use Macaroon! All buttons accept drag-n-drop spells from your spellbook and "feel/function" much like any other button in the default UI or other action bar addons. But if you do decided to expand into the world of macros, be prepared, for you are about to "Feel the power of the macro side..."