Earlier this week Information Architects released the iPhone version of their venerable text editor, and so it's now available for iPhone, iPad (where it started) and OS X.
I use iA Writer on the Mac all the time, and on the iPad whenever I do any sort of long-form writing there, and have been waiting for this iPhone version since the day iA Writer for iPad was released. (Remember, this app is what turned me on to the Nitti Light font, and compelled me to come up with a way to make any app look like it.)
Unfortunately, this small-screen version (like the iPad version) is missing what I feel probably is the best feature of its OS X sibling, namely inline Markdown formatting (it's kind of like syntax highlighting for Markdown). It's also missing the character count and reading time features, which I kind of hate not having.
Despite these drawbacks (all of which I think will be addressed in future updates), I've replaced Notesy on my 1x20 with iA Writer, in an effort to force me to use it for a bit.