I just recently took a group of summer campers here and they loved it!  They are free to work at their own pace and choose whatever piece of pottery makes them happy.  Plus, there was no mess for us to clean up.  Once they were done painting, we got to leave the cleaning to someone else!  It was alot of fun for the kids (I would recommend over 5 years old) and our counselors had a great time painting their own ceramic creations as well.