It really depends on the context, I'd say. Generally speaking, I'm in the camp that thinks the phrase "the N-word" sounds like a kindergarten tattler in action. ("Oooh, Billy said the 'N-word'!") We're grownups. We should write accordingly.
If you're dealing with a straight news story, particularly if the use of the word IS the story, then you've got to clarify with appropriate language ("... used a derogatory term for black people ...") for the sake of being taken seriously.
(There are some who'll argue that, in a news story, you should spell out the word for absolute specificity. I cannot entirely disagree with that philosophy, but I do believe that if you can avoid using it, you're better off making every effort to do so, unless it's essential to know exactly which derogatory term was used.)
If it's a column, a feature or a notebook -- or any other circumstance that bears informality -- you probably can get away with just writing "the N-word" and moving on ... as long as you don't mind the appearance of sanitizing your writing for the sake of so many delicate eyes.