Actually, the new features introduced in C# increases developer productivity quite a bit. More importantly they increase the readability of code by cutting down on the repetitive stuff. Once some one uses LINQ, lambdas and dynamics its hard to go back.
Go look at any documentation or discussion of any non-Java language, and see their examples of using their sequence abstractions, or generators (yield), or first-class functions. Those are not ideas which are unique to C#.
If you just want to see a piece of code in C# that would have to be written totally differently in Java to be readable (unless you use some quite abstract third-party libraries like Guava to help) I picked one of my Stack Overflow answers at random: http://stackoverflow.com/questions/2966592/how-to-refactor-t...
... and yes, as a Java developer, I use Guava once in a while and I do JavaScript as part of my job as well and I do appreciate first-class function.
Typically the problems that functional features solve are filtering and transformation and yet most often than not I happen to solve them at the SQL layer (be it JPQL or straight up SQL).
Once you start thinking of your object model as data, you can do amazing things. Want to find all the types in your system that implement an interface and spin them up?
var rules =
AppDomain.CurrentDomain.GetAssemblies
.SelectMany(a => a.GetTypes())
.Where(t => typeof(ISecurityRule).IsAssignableFrom(t))
.Select(t => Activator.CreateInstance() as ISecurityRule)
.OrderBy(r => r.Priority);
You can then run a chain of responsibility by writing
var allowed = rules.First(r => r.Check(someObject) != null);
//Check returns null when a rule isn't relevant to the object being checked
it's pretty sweet for metaprogramming when you can run queries against your codebase
