I will start this off by admitting that I am a little biased in that I have never been a fan of King Kong. Irregardless, I will try to be unbiased in my review. Overall, the movie was entertaining. It lacked the amazing cinematography of the 2014 Godzilla movie but still outshined King of the Monsters in that aspect. That being said, there were many points I felt it was lacking.
Spoilers Ahead: In King of the Monsters, we learn that Godzilla travels using subterranean pathways. In this movie, it is revealed that there is an entire subterranean world. Within this world, the gravity is altered, there are new monsters, and there are ruins left by King Kong's ancestors. The ruins were honestly predictable because up until that point they were heavily hinted at. Also, it was extremely cliche that there are axes at these ruins that seem to be perfectly constructed to wield against Godzilla since they absorb his beam attacks. It was super cliche. It was also never revealed how this subterranean world might relate to Godzilla with how he uses subterranean tunnels to travel.
Another confusing aspect is when they say that Godzilla's ancestors have historically fought with King Kong's ancestors. If this were the case, why wasnt this mentioned in King of the Monsters when they found records of Godzilla fighting Ghidora? Also, did Ghirdora battle both the Kongs and the Godzillas or just the Godzillas? How old does this make Godzilla and Kong?
Another question is where the other titans from King of the Monsters went to after the movie and where they were during Godzilla vs. Kong.
Another issue with the movie is the lackluster appearance of Mechagodzilla. The amount of screen time that Mechagodzilla got made it feel like such an underwhelming threat. In the 2014 Godzilla, the Mutos collectively damage areas in Japan, Hawaii, Nevada, and California. In King of the Monsters, Ghidora travels thousands of miles in a hurricane of it's own creation and proceeds to beat down a huge fire bird before heading to the U.S. and causing havoc there. Mehcagodzilla barely made it out from underground and into Hong Kong to beat up Godzilla a bit before getting beaten down by Kong after Godzilla helps Kong charge his axe. It was pretty obvious throughout the movie that Godzilla and King would team up, but the overarching villain of Mechagodzilla seemed like such a mediocre threat. Especially after being hinted at for so long after the extra scene in King of the Monsters.
There were also characters in the movie that felt redundant to the plot and overall unnecessary. The movie was definitely centered around King Kong rather than Godzilla, and it was disappointing that they didnt get even amounts of story within the movie. Instead, they focus on 2 new characters and Maddie as they break into the Apex headquarters (on accident). I know it is a movie, but the security for Apex is horrendous. Doors are left open and unlocked and hardly any guards or real security. They easily discover secrets about Apex and move around the headquarters before finally getting caught. Yet another cliche aspect of the movie.
Overall, it was an entertaining movie, but it was very cliche and predictable. The villains seemed laughable, and there are many questions that go unanswered.