It has the same basic idea, sorta, but it is quite different in it's own ways. Have you ever seen a yugioh character make fun of the episode creators, for example? That's a classic move in DM. And Shobu's quest is ultimately to become a master at the game, while Yugi's is to find out about the pharaoh's past and all that. (He only becomes the "king of games" in the process...that wasn't what he truly aimed to achieve.)
Personally, I don't think it's a ripoff at all. I think it's weird, unique, and funny--a show that's not half bad, or at least not given enough credit if nothing else.
But I can see how a lot of people don't like it, I guess. It is a very abnormal show.