Bringing the characters to life is some wonderful voice acting talent including James McAvoy as Arthur (you'd never guess he was Scottish from hearing his voice here), Jim Broadbent as Santa himself, Hugh Laurie as Arthur's efficient and constantly annoyed brother Steve, and Bill Nighy, who is particularly good stealing the show as Grandsanta, delivering many of the best one-liners ("They used to say it was impossible to teach women to read!"). Each of the voice performances is distinctive but at the same time not showy - they fit the characters perfectly.
If there's anything majorly wrong with Arthur Christmas it's that it doesn't do much that you're not expecting. It plays it very safe inside the box and is pretty predictable as far as the plot and character beats that it's going to hit. However, when there's this much genuine joy oozing out of every scene I don't think you'll notice that the plot isn't exactly reinventing the act of gift-giving. This is unashamed family adventure with a big dose of heart, wit and charm.