Visual Studio 2017's mobile test recorder makes it easy to record the actions you want to test. Both creating and running the tests against a large variety of real devices to ensure your app will work well a majority of your customers, if not all. The biggest challenge in mobile development is testing. For C# apps you can use Xamarin for up to 80% code sharing when building native apps. If you are a C++ or JavaScript developer, you can use Cordova or Ionic to build sharable code. Visual Studio makes it easy to use your existing skills in C#, JavaScript, and C++ to build mobile application for Android, iOS, and Windows devices.
Of particular note is that Microsoft is making it easier to build and test mobile applications.
As for what developers will find in the Visual Studio Release Candidate, there's a ton to look forward to - a lot of which is covered in the embedded video above.
