Oh, I knew Capote had written it. In fact, it wasn't even a book but a novella that was entirely different from the movie. There were some similarities, but if you read the novella you barely recognize it as this movie. Capote was unhappy with the casting of Audrey Hepburn, he wanted Marilyn Monroe. Hepburn was not at all like he had envisioned Holly. But she (Hepburn) will forever be identified with this movie.
Hepburn was pretty and classy, but for some reason I usually didn't like the characters she played, or perhaps I didn't like the way she infused them with her characterizations of them. I didn't like her Eliza character in 'My Fair Lady' or her character in 'Charade'. The two movies of hers that I did like were 'Wait Until Dark' (really liked her in that) and 'Robin and Marian'.