1Writer is a new Markdown editor for both iPhone and iPad. In terms of functionality, it's got a shortcut bar just like other Markdown editors offer and live previews. What makes 1Writer great is the syncing and third party app support it offers.
The interface and design of 1Writer was built with iOS 7 in mind and the developers succeeded. It blends nicely but isn't too overdone. With red menu bars that aren't distracting, you're left with your content. The keyboard contains a shortcut bar along the top row so you can access common Markdown functions just as you'd expect.
You can choose to sync your 1Writer content with either Dropbox or iCloud so all your documents are in sync across any iPhone or iPad you own. There is also support in 1Writer for many third party apps which is really what makes is useable and convenient. Natively you can share and publish your content to Dropbox, Evernote, Twitter, and CloudApp. If you use Day One, there's also support for that.
1Writer supports actions as well so you can add custom URL actions. When sharing documents you can choose to export in plain or formatted text, as well as PDF format.
For users that want a great visual experience paired with great support for custom actions and third party apps, 1Writer is an excellent choice.