Having finally actually read In Cold Blood, I can see why some viewers may have found Capote [blogged] to be a little superfluous. (Having seen the movie first I found parts of the book to be superfluous.)

One thing Capote does, however, that In Cold Blood doesn't, is put Truman Capote at the center of this story. The book version leaves its author very much out of the picture, which is strange, because the story of why this atrocity so resonated with Capote is interesting and important, and because (if the portrayal in the movie is to be believed) Capote thrust himself into the proceedings of the case far more than an objective, journalistically neutral stance would ever allow.