These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Awesome Music: "Scrooge". "One More Sleep 'til Christmas". "Marley and Marley". "Bless Us All". "With a Thankful Heart".
Broken Base: "When Love Is Gone". Dear lord, "When Love Is Gone". You will find fans who feel the movie plays fine without the sequence as it did in the theatrical release and some who feel the addition added to the film's quality. The debate has certainly been blown out of proportion on Muppet fan sites plenty of times, especially when the 2012 Blu-ray release used the theatrical print.
Critic-Proof: It wasn't totally panned on release, but it got mixed reviews from critics. Talk to most Muppets and/or Dickens fans today, though, and they'll almost certainly tell you that the movie was very good and stands among the best adaptations of the story by a long shot.
Crosses the Line Twice: Jacob and Robert Marley reminiscing about the time they shut down an orphanage, joyfully recalling the poor children and their frostbitten teddy bears.
[Scrooge walks by them without putting any change in their bucket]
Ear Worm: Just about every song in the whole movie.
'Thankful Heart' has a very catchy tune.
"Funny Aneurysm" Moment: The choir of elderly lady Muppets joking that Scrooge must be "lonely and sad" is Played for Laughs. Then we discover the truth about his backstory. The ladies were quite close to the truth it seems.
Genius Bonus: Look very closely in one of the crowd sequences. One of the background Muppets is a lobster hanging out of a basement window. This is a reference to the line, "like bad lobster in a dark cellar," one of Charles Dickens' weirder turns of phrase.
Harsher in Hindsight: Tiny Tim's death might be even more heartbreaking in the sense that his puppeteer, Jerry Nelson, is no longer with us.
Likewise, the eerily sad fading of the Ghost of Christmas Present.
He Really Can Act: Many doubted how anyone could replace Jim Henson as Kermit, but after the film, most would say that he's in good hands with Steve Whitmire, though not quite as good as Henson.
Ho Yay: Rizzo randomly kisses Gonzo's nose at one point.
It's not really that random. Gonzo had gotten his nose crushed by door for the sake of Rizzo's jelly beans, and it needn't have happened if Rizzo had just looked in his pockets in the first place.
Older Than They Think: Several years prior, a Muppet-based adaptation of A Christmas Carol appeared in comic form in an issue of Muppet Magazine. Although it was an all-Muppet-character cast (including Sam the Eagle as Scrooge and Animal as Jacob Marley), it did cast Kermit as Bob Cratchet (probably following Disney's casting strategy) and Miss Piggy as his wife; and like the scenario mentioned in the What Could Have Been trope on the Trivia page, Gonzo as the Ghost of Christmas future (he didn't say anything because he forgot his lines).
They Changed It, Now It Sucks: Inverted: The majority of Muppet fans can't stand the fact that the widescreen DVD and Blu-Ray more closely match the original theatrical version, in contrast with the VHS, laserdisc, and pan and scan DVD, by cutting "When Love is Gone."
Uncanny Valley: The Ghost of Christmas Past. The effect of a human-like puppet operated in a water tank and added in via green-sceen, is truly eerie.
It's markedly less strange than the thing described in the book, which is more like an Eldritch Abomination in appearance.
Vindicated by History: Achieving only modest box office when it was first released, likely due to Home Alone 2 taking away a majority of its family audience and due to Disney's platform release system at the time got crushed by Aladdin rather quickly, the film now has a cult following among Muppet fans and people who find it a great Christmas movie.
Visual Effects of Awesome: The first film to ever use a green screen (instead of a blue screen), which allowed a tremendously beautiful blue nighttime flight scene.
The Woobie: Poor Bean Bunny. He has the door slammed in his face, a wreath is hurled at him, and to top it all off, we see him shiver in a pile of newspapers on the street - a reminder of the well-meaning gentlemen's points regarding the poor and homeless - and how, even though "There's Only One More Sleep 'til Christmas", there are still those on the street without food, shelter or family.
WTH, Casting Agency?: "Oh sweet, they're going to do a version of Christmas Carol with Muppets. Fun! Wait, with Sir Michael Caine?!" Of course, it ends up working way, way better than you might initially think. Caine went on record as saying he had a ball with the production, adding that the best way to interact with the Muppets is to treat them all as though they're members of the Royal Shakespeare Company.
Although averted with most of the Muppet characters, who fit their roles like a glove. Highlights include Kermit as the put-upon Bob Crachit, Robin the Frog as Tiny Tim, and Gonzo narrating the movie as Charles Dickens himself.
Piggy as a loving, caring wife. Yeah...
Win the Crowd: People were very skeptical about how well Muppet projects could work without Jim Henson to guide them. This film proved there was still plenty of life in the franchise.