There's always going to be some people who just don't enjoy fantasy, or fiction in general. But I feel most people once they get into the first few minutes of Fellowship warm up to the world of Middle Earth, by the end of the Council of Elrond are eager to see how the mission fares, and usually by the middle part are sucked in enough with the characters that they want to see more. I've seen some people dismissive of the whole thing at the start perk up when introduced to the Shire, and who don't see the bridge scene coming and lose it emotionally.