One of the major issues with the movie is its pacing. The story feels rushed, with little time to develop the characters or explore the world of Terra Formars. The plot twists are predictable, and the dialogue often feels like it's trying to cram too much information into a short amount of time.
Hardcore fans will notice this immediately. The movie combines the first two arcs of the manga (the "Bugs 2" and the "Annex 1" arcs). In doing so, it loses the heartbreaking tragedy of the original. The backstories of characters like Shokichi Komachi (played by Takimoto Mirei) are hinted at but never given room to breathe. You need the tragedy to feel the rage. Without it, the fights are just roach-smashing.
One aspect the film does successfully adapt is the "Bug Procedure." In the lore, characters receive injections of insect DNA to gain superpowers (e.g., the powers of a wasp, spider, or cricket). The transformation sequences and the visualization of these powers are some of the film's highlights. It captures the body horror element of the manga—seeing human limbs morph into insect appendages—and offers some of the most creative fight choreography in the movie.