Obsessives who passionately devoured every minute with the upstairs Crawleys and the downstairs help might very well be annoyed by how little everyone is given to do, and how little any of it matters. Those who never watched a second of the show might be utterly lost and left wondering what the big deal is. For my part, though, I found this feature-film exercise in unmitigated fan service a touching, entertaining reunion with half-forgotten friends, even though it doesn't resemble a movie so much as a highbrow Comic-Con panel in which those on the dais receive thunderous ovations merely for showing up.