This is my goto writing app. It hasn't changed a huge amount over the years, but it doesn't need to. It has everything I want in a writing app - full-screen mode, typewriter scrolling, line focus mode and a choice between dark and light modes as well as page width. It is such a great app to get you writing because once you open a new document, especially in full-screen mode, it's just you and a blank page.
Price is temporarily $5.99 (down from $11.99, which it's been at since 2/2015) and they've made free the in-app purchase publishing features.
They also reduced the price of the iOS version to $2.99 (down from the $5.99 it's been at since 3/2015) and eliminated the IAP from it as well.
Together, for $8.98 you get a solid cross-platform solution that beats apps like IA writer ($9.99, and $3.99 for iOS app) or (the quirky but more full-featured) Ulysses, which costs $44.99 for the Mac app and a whopping $69.98 for the Mac/iOS combo.
Considering the number of people leaving comments like "glorified TextEdit" and "Pages does the same thing in full screen mode", maybe the description of Byword should be clear that it handles directly markdown and multimarkdown. It is, after all, the main reason why you would adopt an application like Byword or IA writer, Ulysses, Texts, Typora, etc.