Seems like they are going to town with the renovation of the Central Station.  Newly designed toilets with relaxing (or not) wallpaper to stare at while you spend a penny (well 2zl exactly) have been installed.  Replacing the grot is the  company 2theloo from Holland and they are certainly an improvement on the previous public conveniences.  You can also purchase drinks and other items before or after your trip.  Check them out at 2theloo.com