Is the author fair in his description of the main character? Explain why or why not ?

Diedrich Knickerbocker is a rather unreliable narrator, not because of character flaws but because, as he makes clear in the postscript, he has heard this story from someone else, who did not really believe the story himself. Knickerbocker saves this disclaimer for the postscript, apparently preferring that readers take the story as largely true in order to enjoy it, even though careful readers will be on guard from the beginning, for this is a ghost story. In addition, there are scenes about which Knickerbocker simply could not know the details unless the story had been originally told by Ichabod himself, which is possible, but the provenance of the different elements of the story is not made clear enough to satisfy a historian. A good historian would make efforts to determine which elements are probable before publishing a history he has heard from someone else. But this is not really the point; the reliability of the narrator is not very important because the point is to enjoy a good tale and maybe learn something from the way it is presented.