I don't get it. What's wrong with a teleprompter?

A lot of conservatives attack Obama for using a teleprompter. I don't get it. It seems like a nutty way to attack a guy. How is a teleprompter worse than reading from a piece of paper or notecards, like presidents and world leaders of the past? I see no difference. Perhaps, I'm missing something, I don't know. Fill me in. Explain why using a teleprompter is bad for when giving speeches.