You should think of this post as being aimed at Haskell library writers. The benefit to the application developer is that more and more optimizations are available through identical or nearly identical, familiar interfaces such as those for lists.

In my case (joe average haskell dev) that means I can just stick to normal constructs and switch out the underlying data structure to get the speed benefit. This article actually might lead to such a change in a computer vision package I work on.

You can expect to see this pattern over and over with Haskell, so that by the time you get to data structures that abstract away GPU-based calculations, nobody will be wishing people would just write the darn code in C.