I don't *hate* letterman, but I strongly dislike him. I don't like him because he uses his "entertainment" show as a platform to spew his liberal ideology. For example, see how his interviews of Bush and Gore last year. He was almost openly hostile towards Bush, attacking Bush's positions (especially Alaska) while being totally uninformed.
putting all that aside, it seems like to me, that Letterman was WAAAYYY better on NBC when he was on an hour later. Right now, Leno is better, but I don't watch either of em. Carson was a million times better than either of em.