Different movies, different vibes, different stories.
I've not read any Truman Capote, I was never interested.
Earlier this year there was the Phillip Seymour Hoffman movie, Capote, I thought it was great. But now there is Infamous, an indi film about Truman writing In Cold Blood. Capote didn't make me want to read the book, Infamous did.
Infamous is a very subtle story and I think has a much stronger emotional impact. It slowly sucks you in. I was amazed by Truman's boldness, egotistical attitude and manipulative abilities but there was such a sadness. I think some people would say that the Harper Lee (a very southern sounding, understated Sandra Bullock) was too direct of a narrator (the action was interspersed with interviews with Truman's friends and acquaintances). She was there often and her "observations" of Truman came across, at times as directives to the audience.
Overall, I liked this movie a lot and, like I said, I'm gonna read some Capote.