I helped Ondřej with some of the wording on the home page for SettleApp.
Some advice for developers in general, off the top of my head:
Use words that humans use. (No “algorithms.”)
Use verbs. Verbs are vivid. Verbs trigger people’s imaginations — they picture themselves using the app.
Use curly quotes.
Don’t talk about how you rewrote any part of your app. Nobody cares.
Don’t talk about how it’s native or about how it’s ready for the latest version of the OS. These things are assumed.
Don’t be repetitive.
Cut, cut, cut, cut, cut, cut.