Contested Sequel: Fans frequently debate over whether this was a Surprisingly Improved Sequel to the first movie with much larger stakes and better action and character development, or a Sophomore Slump that didnt add anything to the story and wasted a perfectly good Kaiju fight between Godzilla Earth and Mechagodzilla City.
Not only that, Ghidorah is well known as a planet destroyer. Considering how much Metphies talks about how terrifying he is compared to Godzilla, it was probably one of the few Kaiju to fit.
Captain Obvious Reveal: Ghidorah being the monster that destroyed Metphies' planet.
Awesome Music: "THE SKY FALLS" by artist Xai is a fitting theme song for City.
It helps that the movie criticizes Haruos actions in the previous film, while Haruo himself admits he went too far in his crusade for revenge. His quest for vengence is still present, but his recklessness in pursuit of it is reined in considerably.
Author's Saving Throw: Haruo's personality has been considerably toned down.
It's revealed in the third film that he is in fact the Big Bad, who seeks to summon Ghidorah to "cleanse the earth": he's been subtly manipulating events to cause humanity to despair, and in their desperation offer their souls to his cult and bring forth "the golden demise".
Is he really a good friend of the humans, or is he an evil Bitch in Sheep's Clothing who only trusts Haruo and no one else? Or is he has been manipulating Haruo by siding with him to kill Mulu Elu Galu Gu to gain his trust by doing the right thing?
Alternative Character Interpretation: Metphies once again has an Ambiguously Evil vibe, but he has been more helpful, up until he tells Haruo about Ghidorah.