The syntax for "record types" - elements of named tuples - is really awkward and pollute namespace.

I.e., if I want a module in my app to have two different types containing an element 'customerID' that I'd like to refer by name in that context, then it's a bit painful - and it is a really common need if I need to quickly make a mostly-CRUD webapp, for which otherwise Haskell/Yesod would be as practical as Ruby/Rails.