I have the 4-piece potty training set, though in the Cars pattern, which I purchased on Woot last July. At first my son wanted to use only the folding travel potty seat, and then it slipped on him. Now he refuses to let me set it up, even when we are away from home. He now uses the padded seat exclusively, and he uses the step stool too, though it's not quite tall enough for him to make it all the way up on the potty without an assist. I like that it hangs up on the side of the tank when not in use.
So much for spending out on his fancy Prince Lionheart potty seat and pottyPOD.