The fact that David Cameron is fighting so hard to ban pornography accessibility to legal consenting adults just shows how misguided his priorities are. He is trying to get it removed from the Internet in the U.K which is just ridiculous. This is the only policy of his that I really know, so I would say he is terrible.
David Cameron is not the worst prime minister. He has done some controversial things, but to say he is the worst is pretty out of line. I think overall he is very hard working and while there is a lot of room for improvement, he is a very decent prime minister.