Maybe that's "fairly faithful" as in "It only sleeps around on Tuesdays and Thursdays, it's in an open relationship, and it uses birth control"? Oh, wait, no birth control, since it's going to have two more movies.

Or maybe that's "fairly faithful" in contrast to, say, the Earthsea movie (which had characters who had the same names as the ones in the book, and that was about it).