What is your biggest issue with GvK?

The biggest issue I had with GvK was that the story with Millie Bobby Brown and the other two characters could have been removed and replaced with a more compelling story they don't even touch on in the film, which you would only know about if you read the novelization, and it would be a better movie. For those who don't know, the guy who pilots MechaGodzilla is Serizawa's son which is never revealed in the movie and only in the book. He decides to pilot MechaGodzilla because he wants to kill Godzilla because he believes that Godzilla took time away from him and his father and also killed his father. I think it would have been much better for them to explore that storyline then anything that has to do with Millie Bobby Brown's character. You could even have it that Serizawa's son realizes that he was wrong while someone else pilots MechaGodzilla and goes and tries to shut it down, eventually pouring water on the console that would cause the momentary glitch and give Kong the chance to take down MG. He could then go on to join monarch in honor of his father and become the series new Serizawa like character. It was a massive waste of an incredibly interesting storyline