* Tuples (Proposal: #347)
* Pattern matching (Proposal: #206)
* Records / algebraic data types (Proposal: #206)
* Nullability tracking (Proposal: #227)
* Async streams and disposal (Proposals: #114, #261)
They seem to be really useful for a "more-functional style" of programming.
When comparing these ambitions and the level of transparency to Java's ambitions & transparency, then it seems that C# is (or has) overtaking Java. Combine that to the fact that dotnet is now an opensource project, and MS seems to be more "open" nowadays then Oracle has ever been: I'm stoked about this news.