The changes they have made represent hundreds of hours of work for the
Haskell community. Once languishing core libraries have now been
revitalised. I don't have exact numbers, but a quick look at any of
these libraries, along with a recollection of how they were before,
will show you just how much things are changing for the better.
Now, the next biggest hurdle is text. Also, filepath is unmaintained
(but at least is mostly stable). If anyone knows of a good
maintainer(s) for either of these, please let me know.