It softens up a bit. Probably never be a seat you want to spend hours at a time in, but it does become a little more compliant. For around town it's fine. I did a weekend ride of 450 miles and grew tired of how hard it was.
If you want the JvB rear fender it's the way to go. I may eventually take it to an upholstery shop to have it reworked so it's more comfortable.