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.
Ass Pull: Dr. Nefario and the Super-Serum Antidote
Award Snub: Despicable Me 2 dominated the 2014 Kids' Choice Awards winning "Favorite Voice from an Animated Movie" for Miranda Cosgrove and "Favorite Mobile App," but getting shut out of "Favorite Animated Movie" by Frozen. Yes, Frozen was a lot bigger than DM 2 was, but still, it put a blemish on a despicable night of awards.
Ear Worm: "Another Irish Drinking Song" as sung by the minions.
Pharrell Williams' "Happy" which makes you sing and dance while walking on the streets.
Fan-Preferred Couple: Even though Antonio dumped Margo for another girl, leading to Margo's current "hatred" for boys, many fans have a different idea. Some fanfictions and music videos still pair up Antonio and Margo.
Hilarious in Hindsight: In one trailer, Gru was starting to get a little Papa Wolf when he thought Margo's friend Avery may be a boy. Margo does get a crush on a guy named Antonio later in the movie.
In the first film, Gru tries to keep his supervillain identity a secret by claiming he was a spy. Cut to this movie, and he is hired as a spy for the Anti-Villain league.
Memetic Mutation: The minions' imitation of a fire engine's siren: "BEE-DO BEE-DO BEE-DO....."
The 24-hour music video of "Happy" spawned many covers from people around the world where they sing and dance along with the song. Its title is "Pharrell Williams – Happy – We Are From [name of the city]"
Nightmare Retardant: The Evil Minions. They look like deformed Build-A-Bears and sound like they're vomiting. Not exactly scary is it?
The Scrappy: Much like Gru, there's plenty of people who hate that Chicken.
They Wasted a Perfectly Good Plot: Most of the villains from Despicable Me go unpunished - in fact, don't even appear. Mr. Perkins still presumably runs the Bank of Evil, Miss Hattie presumably still runs the orphanage and neither of them figure in the plot. The sequel instead focuses on a Love Interest for Gru.
It looks like Little Miss Badass Edith will finally get a moment in the spotlight to fight the Monster!Minion in her ninja costume... then Dr. Nefario shows up in the nick of time and injects it with anti-serum.
The Margo/Antonio subplot is immediately dropped after Gru goes Papa Wolf on Antonio. Antonio completely disappears from the plot after that.
Unfortunate Implications: Eduardo and Floyd are really stereotypical, though perhaps Eduardo gets it worse. More than a few Hispanics were uncomfortable with his character's portrayal. There's also the fact that these are the only non-white characters in the movie. One is an irritating Red Herring that vanishes halfway during the movie, and the other is the villain.
Eduardo might have been playing the stereotypical behavior up to keep people from realizing he's really El Macho. Cinco De Mayo isn't even a major holiday in Mexico- it's more of a Chicano thing that got promoted as a big celebration day by beer companies.
Eduardo's son Antonio also carries many of the stereotypical Latin Lover traits...though he isn't involved with his father's nefarious schemes, so that's a plus.
To be fair, Eduardo is portrayed as very suave and affable, willing to dispense helpful advice to Gru before his true colors as El Macho were shown. In addition, his cunning, intelligence, manipulations and sheer badassitude (especially in his younger years) bordered on the magnificent and was a far more credible threat to Gru and his loved ones than Vector, who was just an Ineffectual Sympathetic Villain.
Gru is an absolutely fantastic dad and seems to have no problems taking care of the kids. Despite this, the movie implies that a child isn't truly happy without a mother.
Dr. Nefario abducts and experiments on the Minions that he considers family. When he leaves Gru to find other work, he joins a villain actively working against Gru.
To be fair, as its already been pointed out, he did give them a nice place to stay and its uncertain whether he would view making them stronger and more dangerous as hurting them. Plus initially Eduardo wasn't originally working against Gru, he in fact makes it clear he admires him, and offers him a partnership in ruling the world. Its only when Gru turns him down that Eduardo turns him, which is about the same time Dr. Neffario switches back to Gru's side.