Syntax is the absolute best thing about Haskell and it's ML relatives, especially coming from C++ and Java as I did. It's succinct and very easy to read, without braces, parens and type annotations scattered everywhere. For example, defining a function is as simple as "let f x = ..x.."

The succinctness of Haskell really matters when dealing with non-trial code or types. Just compare the type signtaure of "SelectMany" in C# to an equivalent in Haskell.