"Editorial changed how I use my iPad: I can now work from my mini without worrying about the apps and features I’d miss from my Mac. I want to work from my iPad, because Editorial is a better, faster, more efficient writing and editing environment than Sublime Text 2 on OS X, even considering all the Markdown-related scripts and macros I have in Keyboard Maestro. As a hub that connects apps and text with workflows and native UI elements, Editorial has reinvented the way I use iOS and third-party apps for writing, researching, taking notes, discovering links, and sharing them with other people. For me, Editorial is more than just a text editor."
I don't know if, right now, an app like Editorial could exist in the Android world. It's such a thoughtfully written application, with massive amounts of attention paid to the little bits that iOS doesn't handle well right now (inter-app communication, cloud storage). At $4.99, a price that's considerably less than what comparable destkop apps go for (Sublime Text is $70, Textmate is $54), it's a steal. I optimistically hope that it'll make the developer enough money to continue to fund his insanely good work. He must thing he can; according to most reviews, this app has been in development for nearly a year.
There are, presumably, enough iOS users for whom a powerful text editor is worth $5.
I'm not sure if, even with the growing Android market, there's enough users out there who would pay $5 for a text editor. Certain types of apps (games and system tools) seem to work in the Android market, but I'm not sure a text editor is one of them.