It's an interesting service, however, I feel like this would create apps that don't native on the intended operating system and are kind of bland.

iOS's native functions and hardware operate much differently from Android's, which is completely different from Windows Phone. Android has an hardware based back button, and the iPhone doesn't, which means you'd have a different UI for the iPhone and Android version (back button in top left on iPhone, no back button on Android). The iPhone has front facing camera which can be incorporated into apps, where as most Android phones don't have a front cam yet.

I'm sure they'll figure out the issues pretty quickly though.