Big-Lipped Alligator Moment: The movie is grounded in reality (well, apart from the way the characters act, at least), but the final shot ends with one of the rooftop Frosties tipping its hat to the viewers as Marty, as Santa, flies by overhead in a Volkswagen Bug pulled by reindeer.
Bile Fascination: The primary interest most people have in it is how it shows everything wrong with Christmas movies.
Darkness-Induced Audience Apathy: Both Luther and the neighbors are both very unsympathetic, so that many viewers don't care about either of them. Luther's grievances are completely reasonable, but he's such an unlikeable jerk that it becomes hard to root for him either.
Designated Hero: The neighbors, all of whom have gone out of their way to force their Christmas traditions and the competition upon the Kranks.
Designated Villain: Luther and Nora. Who knew not celebrating Christmas or simply celebrating it your own way was considered a borderline criminal offense?
Ending Fatigue: The moment where Luther gives his cruise tickets to his neighbors would have made a nice note for the film to go out on. Unfortunately it drags on way past this point, and before the actual ending we get more bits including another neighbor being stuck on the Kranks' roof, the robber getting loose and then being caught by Luther, and the aforementioned Big-Lipped Alligator Moment.
Family-Unfriendly Aesop: Whatever your motivation, acting outside of the established norm and rejecting conformity is a fast way to make enemies of those who like the status quo (which is usually the majority of people around you).
Heartwarming Moment: As bad as this movie is, one moment that stands out from the rest. Luther offering the cruise tickets to his neighbor, Walt, and his dying wife as a Christmas present for them. Even more heartwarming considering that Luther and Walt have done nothing, but squabble for most of the movie.
Informed Wrongness: In the end the audience is somehow supposed to agree with the neighbours that the Kranks are being selfish in wanting to celebrate the holidays on their own terms and not be bullied into conforming with everyone else over a tacky competition. Luther insisting that they not even give any money to charity/the church seems to have been thrown it explicitly to make this go down easier.
Jerkass Woobie: As JonTron put it, Luther would be just the most irredeemable asshole who just goes out of his way to piss people off in other circumstances, but considering the situation, you're more likely to sympathize because of all the crap he goes through.
Mood Whiplash: The news of a neighbor coming down with cancer for the third time or of Blair's marriage to a man she only just started dating are quickly glossed over as the madness on the block carries on.
The Scrappy: Odds are you will not be taking the sides of the neighbors for their obsessive effort to force the Kranks to celebrate the holidays in the way that only they see fit. Also doubles as a massive case of Unintentionally Unsympathetic.
Snark Bait: As a Christmas movie with a pro-conformity, pro-commercial message, it is a popular target in the discussion of "bad" Christmas movies.
What could have been a wickedly sharp satire on the kind of people who have made Christmas the beast it is gets ruined when the movie expects us to be on their side. This film could have been an amazing dark comedy or even a straightforward thriller a la a Christmas-tinged Get Out if it had even an ounce of irony or self-awareness about how horrifying its yuletide Stepford Suburbia really is.
Some reviewers think the movie would have been much better had it been about the Kranks actually on the cruise.
The brief climax of the electricity failing, and thus the neighbours' superficial grandiose take on Christmas being destroyed as well could have worked as a good compromise, with both sides having to appreciate the actual unselfish spirit of Christmas. Unfortunately the problem is fixed, and they get things completely their way.
Unfortunate Implications: The very fact that not celebrating Christmas is seen as some kind of moral or even legal offense is bad enough, but then the film hammers home the idea that fighting against the status quo no matter how much you disagree with it will get you nowhere and you should accept it for what it is. Roger Ebertnoticed.
What an Idiot!: Both the crook that the cops pick up near the end of the movie, and the cops themselves. The latter because, instead of driving him down to the station after they drop off Blair and her fiancee, decide to leave the man unattended in their car while they goes to the Kranks' party. The former because, even though he manages to escape the car with the help of a gullible kid, decides that instead of just counting his blessings and making a run for it (or even going to one of the dozens of empty houses on the block), he'll just break into the house the policemen are in and steal some things.
The Woobie: Both of the Kranks. But Nora especially during the ham scene. And somehow the movie expected viewers to be against them for skipping Christmas.