C# 7.0 adds a number of new features and brings a focus on data consumption, code simplification and performance. Perhaps the biggest features are tuples, which make it easy to have multiple results, and pattern matching which simplifies code that is conditional on the shape of data. But there are many other features big and small. We hope that they all combine to make your code more efficient and clear, and you more happy and productive. Please use the “send feedback” button at the top of the Visual Studio window to tell us if something is not working as you expect, or if you have thoughts on improvement of the features.
Source: What’s New in C# 7.0 | .NET Blog