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.
Broken Base: Over Lloyd being the Green Ninja. Many were expecting Kai or Zane to be the one awarded the title.
Also over the increased amount of sci-fi elements in the series, particularly the Ninja getting their vehicles in Snakebit and Zane turning out to be a Nindroid in Tick Tock.
A Leitmotif, first heard in "The Fire Temple", which appears to be a theme for Lord and Lloyd Garmadon as it plays in scenes where they are together. Quite fittingly, it's a tragic-sounding melody due to the destined battle between father and son. It also receives an espeically epic arrangement heard in "Fall of the Green Ninja" when Lloyd pleads to his father to help him fight back against the Overlord.
The Serpentine, especially Skales and Pythor, receive extensive treatment of this by the fandom. Somehow, these bloodthirsty and treacherous villains are interpreted as innocent Woobies who only want a hug.
Lord Garmadon suffers from this to a degree as well, though it's more justified given how he is depicted as a Tragic Villain from Season 2 onward.
Ear Worm: The opening song — "Nin-jah-go, Nin-jah-go!"...
Ho Yay: Although it doesn't happen often thanks to the show's Target Audience, it still occurs on occasion.
In "Can of Worms", Zane rode on Cole's back the entire way up a mountain, despite the fact that he was more than capable of doing it on his own. Then, there was this particularly lovely exchange upon facing one of the Serpentine Generals.
Skalidor (to Zane): Look who's calling who pathetic... Pinky.
Cole: Only I call him Pinky!
Not to mention in "Darkness Shall Rise", there was this:
Narm/Narm Charm: It's a little hard to take the plot twists seriously when the characters are still cute-as-a-button minifigures. This doesn't take away awesome moments however and the characters usually act normal and not like they live in some toy chest.
The scene were Skales tries to capture Lloyd...by slowing descending down on a window-washing lift, outside.
When Lord Garmadon is possessed by the Overlord, something about his face looks... off. Given that this series gave us cool reptilian faces such as the Great Devourer and, eventually, the Overlord's final form, there's something not quite right about the design of this face.
Ugly Cute: Some of the Serpentine fall under this on certain occasions, when they're serving as a comic relief rather than serious villains.
The entire final battle is made of this. Lloyd's Golden Dragon is particularly impressive.
The Woobie: Zane's No Social Skills, background as orphan unlike all the rest, and frustration others have because of his different ways can make him this at times.
Averted now that he knows where he came from.
Or made so many times worse.
Lloyd is also becoming a woobie. First of all he was tricked and kidnapped by Pythor. Then thrown into his prophecy of defeating his father and devoting most of his life to training. Finally he has quite literally has had his entire childhood taken away from him.
Iron Woobie: Lord Garmadon is sort of becoming this as season 2 goes on.