Connor Denney’s review published on Letterboxd:
This is how adaptations should be made. Too often will a screenwriter or director approach source material with extreme adulation, unsureness, or even fear, leading the adapted work to be a bland attempt at capturing the "proper" narrative as accurately (or even worse--as "realistically") as possible. While this might please the most die-hard fans of the original works (or at least those without much of an imagination for the power of cinema) by making their job of visualizing the work as they read it much easier, it often makes for a film like The Girl with the Dragon Tattoo or most members of the Harry Potter series, movies that try so hard to stick to some very safe replication of an already known story that they disdain any sort of experimentation and end up failing to look past the elements of the work that have already been created by the original author. And beyond pure entertainment, or perhaps the opening up of a work to a new audience (for example, the transition of childhood classic Where the Wild Things Are into an interesting film geared toward adults a few years ago), these films are akin to plagiarism: the value added by the team of creative artists whose task it was to adapt the novel (or short story, or short film, or stage play) for the screen is so minimal as to be nearly unnoticeable.
For this reason, The Muppet Christmas Carol might be one of the best adaptations I have ever seen, even if its other qualities prevent it from being even close to a great film. It engages with its source material in a way that few films do. Perhaps its property as essentially a children's comedy gives it a bit more carte blanche to experiment with the nature of narrative, but films for older audiences are certainly able to act in a similar manner. Just last year Darren Aronofsky's Noah engaged with its source material, the Bible, with a fundamental sense of disgust and disagreement. While Noah did not quite work because of reasons not limited to a strange and uncomfortable tension between the work and its source, The Muppet Christmas Carol surpasses its mandate. Presumably a film made to entertain children as it recounts the classic story of Ebenezer Scrooge and his discovery of the joys of being a good guy, the Muppets' haphazard deconstruction of Dickens's work (deconstruction might be too formal of a word--destruction? demolition?) brings the 3rd person to life and engages him within the narrative. Narrators have been around since ancient Greece, and even in those days did they interact with the material, but has a piece ever questioned its own composition at the very time that it is being composed?
While the film may contain a bit too much childish slapstick for my liking (Gonzo and Rizzo probably did not need to be knocked off the balcony due to Scrooge's opening of the window so many times), I am sure that it will continue to entertain those in its target audience, as it entertained me when I was younger. That said, the joyous guest appearances by the entire Muppet ensemble makes for excellent comedy, contributing even more to the sense that this is less of an adaptation of A Christmas Carol than it is an infiltration of the novella by Jim Henson's gang. We are supposed to laugh when Bob Cratchit's wife turns out to be played by Miss Piggy, and we do, our knowledge of the tumultuous relationship between the two "actors" working in a similar way to our appreciation of Michael Keaton and Edward Norton's characters in Birdman, though perhaps with a little less social relevance (and potentially fewer problematic elements, though I will leave that for another time). In this sense, The Muppet Christmas Carol is a cultural event, a film that relies on our knowledge of both the Muppets and A Christmas Carol to be effectively seen.
The Muppet Christmas Carol has so much more than meets the eye. It is not that it is a good film in spite of the omnipresence of the Muppets, but rather because of the omnipresence of the Muppets, or more specifically because of how the omnipresence of the Muppets is handled. In a sense, the way in which the film is not faithful at all to the straightforward narrative of A Christmas Carol makes it even more respectful to its source, as it understands the significance of Dickens's book and knows that any typical rendition of the story will fail in comparison to the original. It knew that the only way it could succeed is if it did something that Dickens could not. It might be hyperbole to call The Muppet Christmas Carol the epitome of cinema, but how many other films truly achieve something that can be achieved with no other medium?