I own a number of journalling apps, on both iOS and Mac, and this is easily my favourite. It has by far the cleanest interface and gets out of your way so that you can focus on getting down your thoughts. It has full-screen mode with typewriter scrolling, word count and goal, multiple journals and a user-configurable template. It also syncs flawlessly to the iOS versions.
I was a long-time user of viJournal, and I now, finally, feel like I have a new home for my journal - none of the other apps have ever felt quite right.