HTML 5 has proven to not be the silver bullet everyone hoped for. By their own admission, Facebook's biggest mistake was betting on HTML 5. While it works well for content, anything more than that needs native performance. Mobile users demand native performance. The first few seconds of any mobile user's experience is the most important. Users will uninstall or never again open an app if they are dissatisfied in those crucial first moments. So what is the answer if it's not HTML 5? There's a case to be made that it's Xamarin.