Are you comfortable with C#? Then you are ready to learn how to build both iOS and android applications using Xamarin. With the increasing numbers of smartphone users, mobile devices have become the first step for many users when they are looking for product reviews, shopping or playing games. You need to be able to develop in a single code base using one language and then use it across multiple platforms.
Using Xamarin for you mobile app development just makes sense. You only need one language, C#. Because you are using a single code base it is a faster time to market for your projects and because you are using a single language, fewer bugs to track down and fix.