I've only had mine for a few weeks. I'm running them at about 40 psi, but I should up that to 42 psi, per Gaijin here on mud. No, they aren't harsh compared to the highway tires that they replaced; they ride quite well. They seem to be less harsh over potholes and the like. They are slightly noisier at highway speeds -- it is noticeable, but not in any way objectionable. I have lost about 1 mpg with these tires.
I've only had them out in snow once. They were better than the all season tires that they replaced. That said, they are still basically brand new and snow performance seems to degrade quickly as tires wear. So we will see how well they do next year with another 10-15k on them.
They are probably not as good in snow as a dedicated snow tire like Nokian Hakkepelittas or Bridgestone Blizzaks. If you get a lot of ice, then I would consider getting a second set of tires and go with dedicated snow tires in the winter. Real snow tires have a lot of sipes that help on ice. The K02s don't have a lot of sipes.