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.
Did Finn's dad let the baby sister play with the same Lego collection to be fair, or because he wanted to teach Finn a lesson about the difficulties of sharing your Legos with kids?
Some fans wonder if The Man Upstairs had some degree of OCD or was in a mid-life crisis due to his obsession with order and control for his Lego world. As stated elsewhere on this page- even most adult fans are against the idea of gluing their Legos in place.
Anticlimax Boss: Lord Business never actually gets into a real fight with any of the heroes- when he is in a fight, he usually uses sheer numbers or his superweapons to cheat. At the climax, some fans who adored the movie admitted that they would have preferred Emmet showing his Master Builder powers off and beating the person who took down The Obi-Wan.
Awesome Ego: Batman in this film is a hugely egotistical character, unlike most true depictions of him. But he'sfriggin'Batman; if anyone deserves to have an ego, it's him.
The fact that it is mostly CGI that tries to look like stop-motion rather than straight-up stop-motion is a big detractor to many, though this is also forgiven by many others considering that much of the film is of a scale far too large for stop motion to be practical, such as scenes where an entire LEGO city is animated or the surface of the ocean (waves and all) is built entirely from bricks.
There's also a handful of people that feel that the film's Sequel Hook interferes with the otherwise complete ending. It's mostly because it sets up a sudden plot thread for a quick joke instead of bringing more of a closure to the film. Naturally there are those that found it clever and ridiculously funny and like it for that.
Some fans who otherwise adore the film aren't fans of the plot-twist that the entire movie is just a story in Finn's head, with many saying that the Lego Universe being just that would have been better than inserting Finn and "The Man Upstairs." Others are a fan of the emotional elements it brings to the table, as well as the completeness of the lesson on creativity. There's also those who argue the opposite, that it's a great twist, but it was a mistake to have the Lego world actually be real, with Emmet able to affect the "real" world.
Canon Discontinuity: Possibly averted. Lego City, and Lego Chima which are both currently huge Lego franchises right now, are oddly absent. Though possibly justified as they have to save some playsets for the sequel. As well as Word of God says that all Lego universes are canon, and Lego City has already been established as the homeworld of ClutchPowers so if they do introduce Lego City they may be obligated to have a crossover.
There's also the more-bizzare Unicopy/Kittycops (Bad Cop/Good Cop and Uni-Kitty) pairing, due to the two having split personalities, despite the fact that these two also shared little screen time together.
The one word that can be used to describe fans' reactions to Johnny Thunder's cameo appearances is "rejoicing". Made better by the fact that he was released as an updated minifigure in the Super Secret Police Dropship set.
When Vitruvius is addressing the Master Builders, he pronounces Michelangelo differently when referring to the Renaissance artist and the Ninja Turtle. Specifically, Renaissance Michelangelo is pronounced using the correct Italian format.
Just like in Wedding Crashers, Will Ferrell is mentioned as an unseen special character (here, as The Man Upstairs) who is finally revealed at the end, emerging from a shadowy stairway.
"Everything is Awesome", a generic pop song about everything, well, being awesome, was mentioned as "topping the charts again" in-universe. The film came out shortly after Pharrell Williams' "Happy", a generic pop song about being, well, happy, was nominated for an Oscar and subsequently began a 10-week chart-topping run. Given that, in-universe, "Everything is Awesome" is a pacifying tool used by the President Business to keep the citizens mindlessly entertained, the parallel can be both hilarious and unnerving.
Robot DJs: We love listening to this song over and over again!
In the Lego Adaptation GameLego Batman 2, Batman is also a jerk who really needs to learn how to cooperate. THIS Lego Batman was written independently but he's oddly similar to an exaggerated version of that, into someone who actually knows he's cool (or is trying way too hard to be cool, anyway).
Bad Cop's loyalty to Lord Business is seen as this by some.
Benny and Metalbeard get a bit as well, given that they are paired together in the tower job, Benny comments joyfully on Metalbeard returning to save the crew from drowning, and Benny has a tendency to hide behind/stand under/cling to Metalbeard's legs.
Subverted by Lord Business when he erases Good Cop's face and forces Bad Cop to use the Kragle on his own parents. This is before The Reveal that he just wants to be special, as well as the fact that the Kragle's effects are easily undone.
Some Lego fans consider Lord Business's entire plot (to glue all the Legos together) this as well.
Christy Lemire: You know that old cliched response after walking out of a movie or a play: “I laughed, I cried”? This time, it’s really true. I laughed my ass off — and then I cried. A 3-D, animated movie about a bunch of tiny pieces of plastic made me cry.
Rooting for the Empire: See below. Many an adult Lego fan that had to deal with children invading their collection can empathize with The Man Upstairs - Except for the glue, however, most adult fans are completely against that.
But it's also averted, as a few parents would end up feeling guilty if they made their children play with Legos as long as they used the instructions.
She Really Can Act: Alison Brie as Uni-Kitty. Special mention goes to the scene where Uni-Kitty is crying over Cloud Cuckooland's destruction.
Squick: Metalbeard's story finishes with him escaping with nothing but his head and sundry organs; represented in-thank Heaven-silhouette by a long rope and a few specks. Obviously his intestines and all them pod-shaped insides. Also counts as Getting Crap Past the Radar.
While Finn's dad is portrayed as in the wrong, keeping his kids from playing with the (often expensive) collector sets until they were old enough to understand how not to lose important pieces and such is perfectly reasonable. Granted, he missed the signs that Finn finally was old enough.
Emmet's "double-decker couch" idea is mercilessly mocked as a dumb idea to make Emmet look pathetic, yet many fans think it's a brilliant concept. A few admit that the whole legs dangling thing might need looking at, but aside from that it's still seen as a good idea.
Sweet Dreams Fuel: Uni-Kitty is filled with this trope. Word of God even says she was meant to be "someone cute, innocent, and utterly adorable".
Take That, Scrappy!: The Duplo brick aliens being the new villains at the end is Lego making a jab at a product of theirs that even most of their own fans openly hate.
Middle Zealand is described in a very specific montage, yet our heroes just drive through it within a minute and arrive at Cloud Cuckoo Land without any development in that realm! Guess the writers couldn't think up good enough gags for it.
Unfortunate Implications: Fox Business devoted a segment to point out that the movie could be considered "anti-business" and that the villain looked somewhat like former GOP Presidential Candidate Mitt Romney.
Wangst: Played for Laughs in regards to the song that Batman wrote for Wyldstyle - it features lyrics almost entirely composed of variants of the word "darkness", but he also notes that being rich helps him with his trouble.
What Do You Mean, It's Not Political?: Some have seen parallels to modern America with the vapid and over exposed pop culture, corrupt politicians who spy on the public, and violent police. Also, some have criticized it as being anti-business.
The Woobie: Emmet, he's a very friendly guy but then the fact that a lot of people he considered friends don't really care much about him or even remember who he was. It's not really hard to feel sorry for him.
Unikitty, as she watches the destruction of Cloud Cuckoo Land.