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.
Squick: It's implied that Marie marries the 15-year-old Nutcracker Prince at the tender age of eight, although to be fair, the book doesn't specify how much time passes between certain events.
Values Dissonance: In these times it was more or less normal to have middle-to-high-class young girls marrying older men, though for that to happen, Marie would've been at least some years older.
At least one animated adaptation ages up Marie to around 12-13, which is the "marriageable" age mentioned above. The Prince/Young Drosselmeier remains more or less his age: this means a 12-year-old girl falls for/marries a boy around 2/3 years older.
Or Pas De Deux. It's incredibly romantic, and was written on a dare to write a piece of music that played the scale in order.
Ballet critic Arlene Croce pointed out the particular chords bear more than a passing resemblance to a very common Russian Orthodox funerary piece. The theory goes it was in part a musical tribute to Tchaikovksy's Dead Little Sister.
Big Lipped Alligator Moment: Mother Ginger is very much this. While the other dances in Act 2 are frequently lovely balletic displays, Mother Ginger and her children are played chiefly for laughs.
Freud Was Right: The Baryshnikov version, once aired on PBS every Christmas, features adults in the roles of the Nutcracker and Clara...even though the latter is still playing a young girlnote albeit because anyone dancing a pas de deux with Mikhail Baryshnikov would have to be a phenomenal dancer, something no one young enough to look the part could have the training to manage. Gelsey Kirkland, on the other hand.... (This adds a certain frisson to their pas de deux.) The Mouse King is the nastiest of the party-goers, and the other gentlemen show up as the rest of the mice. Meanwhile, the whole ballet is orchestrated as a coming-of-age for Clara, who gets a hint of romance with the Nutcracker Prince before being brought back by the ever-watchful Drosselmeyer.
The 1983 Pacific Northwest Ballet version filmed as Nutcracker — The Motion Picture (1986) had set and costume designs by Maurice Sendak and also takes on coming-of-age themes. Clara is played by a young girl in Act One, and Drosselmeyer is, as Roger Ebert and other critics noted, at least a bit of a Dirty Old Man who plunges her into the battle of the Nutcracker and Mouse King. Once the King is killed, the now-human Nutcracker and Clara are played by adults. They travel to a kingdom ruled by a pasha, played by the same actor as Drosselmeyer, who is jealous of their romance and tries to distract her with his dancing subjects (who replace the Land of Sweets characters).
Money, Dear Boy: Despite the objections noted below, there are sound financial reasons for staging it every year, not least because it often draws in audiences who don't normally attend the ballet.
Tastes Like Diabetes: A common criticism from serious ballet fans, especially ones who are tired of seeing companies re-stage The Nutcracker every year rather than embracing edgier (though less commercial) fare. Give them their due; the entire second half of the ballet does take place in the "Land of Sweets."
Thanks to the number of dancers now using social media, it's hard to avoid noticing that they're often not so fond of the ballet, either, especially in companies where they may do nothing else for two months straight.