Feynman was not an adherent of string theory and very sceptical about it. He was among the those who had been interviewed by P. Davies and J. Brown. The interview is not very long, only a few pages. It is especially recommended to read those pages, not because of Feynman's attitude toward string theory but because, in the interview, he tells something that concerns everybody and can also be understood by everybody. Even if you don't have time to read, read that!