I work on the Start menu. It's just a UWP XAML app with Models and ViewModels written in C++/Cx, as are most of the new Shell features and built-in apps--although some of the newer ones, like Maps and Xbox, are in XAML/C#/.Net Native. Even the UI frame of Edge is in XAML, and the new Office UWP apps are too. I encourage everyone here to give UWP apps a shot; we dogfooded the dev platform to ensure it was stable and fast, and XAML really is a pleasure to use. It's come a long way since WPF.