Lego Ninjago movie is a disaster.
And it's Warner Bros.' own fault, really. Their thirst for franchises has gotten the better of them, first with the DCEU and now with Lego.
The main thing is that they pulled the NSMB mistake by releasing two Lego films in the same year that are very similar to each other in theme and beats (hence the accusations that the brand is growing stale). If The Lego Ninjago Movie was remarkably very different from the past films, this wouldn't be too much of a problem, but from what I've heard / talked to someone who's a fan of the original show but didn't like the movie, they brought in a ton of people who changed a lot from the show the film's based on to make it more similar to the Lego theatrical films. The six main characters, for example, go to school in the film (they didn't in the TV show), and have a different set of voice actors.
Lego Ninjago Movie's credentials list three directors, five producers, and seven writers overall (five for story, seven for screenplay). Only two of those writers came from the TV series, and they only worked on the screenplay. Lego Movie and Lego Batman Movie had significantly less directors/producers/writers on their projects. A perfect example of too many cooks spoiling the soup.