Pro tip: Do user testing. Watch unbiased, new people try to use your app. Laugh. Cry. Make it better.
@broox @tolar Make sure those people are different than you in race, gender, creed, country of origin, and everything else.
@broox @tolar If you've never watched a German use your app you've never lived.
Even better, do rough prototypes on paper before you start to code. Guaranteed to save you time and misery later on.
Beats the alternative of never testing and assuming it's great, then flipping out when no one else embraces your awesome idea.