There are essentially two kinds of adaptations of A Christmas Carol: There are the versions that try hard to stick to the original story and take the material seriously, to get at the genuine emotion and social commentary inherent in Charles Dickens' novel. I've watched two of those versions this month, and Robert Zemeckis' recent motion-capture adaptation is another. But the second kind is far more common now that the story is so ubiquitous: Those are the versions that use the familiarity of the source material to riff on the story's themes, and mash-up other elements of pop culture with Dickens' well-known story beats. Every TV show that puts its characters through a version of the story falls in that category, as do most adaptations these days, since it's difficult to tell this story with a straight face anymore (something Zemeckis found out the hard way).
The Muppet Christmas Carol is definitely in that latter category, although it exhibits surprising fidelity to Dickens, both in its attempts to take Scrooge seriously and in its liberal use of the author's original prose. Still, this version's Scrooge (Michael Caine, lending plenty of gravitas to the production) is fairly toothless, and the movie is more interested in humorous bits with Gonzo, Kermit, Miss Piggy, etc. than in telling a serious story. That's fine, though, since the Muppet characters are quite amusing, and the light tone fits them perfectly. Muppet weirdo Gonzo gets the most screen time as "Charles Dickens," serving as a sort of Greek chorus (along with Rizzo the rat) and delivering a good chunk of actual Dickens narration. Kermit and Miss Piggy have small roles for such important Muppets, but Kermit does get a spotlight song as Bob Cratchit, at least.
The funniest bits come courtesy of bitter hecklers Statler and Waldorf, who serve as Jacob Marley and his heretofore unmentioned brother Robert, and of course Gonzo himself, who is as much the star of the movie as Caine is. And the way that Caine plays Scrooge completely straight, if a bit watered down, allows the Muppets to be as zany as they want to be without undermining the simple lessons of the story. This version is mainly for kids, but it doesn't shy away from Scrooge facing down his own grave or learning how happy people might be when he dies. The bland songs are the only part of the movie that fall flat, but they're more forgettable than bad. Telling this story over again might not be the best use of the Muppets, but they mostly make it worth sitting through one more time.
The True Meaning of Christmas: Just be a nice person.