I was a big proponent of functional C# and even started writing s book on it, back in 2008. But my final conclusion is that C# is ultimately too clumsy and verbose to really work with highly generic and highly functional code. You end up fighting too much.

This librarydoes look nice, and top-level findings really do make a difference. But I doubt it's enough to really make up for all of C#'s shortcomings. But if you're stuck with C#, might as well make the best out it.