I think it detracts from the main premise of a detective show. Not that it becomes automatically bad; all the other characters carry it enough. But it would be a truly great show if Light was as intelligent as he is presented to be.
As it is, Death Note is less of a detective show involving supernatural elements, but a show about supernatural involving detective elements. The story I got from it wasn't of two masterminds clashing in a battle of strategy, but of a vulnerable teenager being used by supernatural entities for their amusement. Which makes me feel misled.