Project Hail Mary is a good movie, not a great one, partly because it is a merely good adaptation of the book. I do not demand slovenly devotion to the source material because movies are a different art form than books. Allowances must be made. Often, true fidelity to the source material means cutting things out, rearranging key scenes, merging characters, and so on. Great movies can be made from mediocre source material as the filmmakers find the core of what works, polish it, and present it with a new shine and perspective (The Godfather). A false sense of loyalty, however, forces a rigidity that breaks instead of bending and flowing with the needs of the medium.
One example is the first Harry Potter movie, which feels like a checklist in movie form. Sure, it’s faithful to the book, but it’s not a very good movie. Bland. Lifeless. By contrast, the third Harry Potter movie took some liberties, allowed an infusion of the director’s unique vision, and ended up being a good movie, still recognizably based on the Prisoner of Azkaban. It had a beating heart of its own, instead of trying to squeeze blood from the raw words on the page, helped by the fact that the child actors have better experience at their craft.
Project Hail Mary does an admirable job of having its own beating heart. It takes liberties. It modifies the story to successfully translate a first-person narrative into something that works for cinema, and without resorting to voice-over. It even manages to be more family-friendly than the book, cutting out gratuitous cursing and sexual references. I applaud the deft touch of bleach.
The performances are great. Rocky the alien is well-done. Most of the story and critical moments are intact.
However, it makes a critical error by removing a load-bearing narrative point, one that is important for the main character’s arc. Without it, our protagonist doesn’t actually grow all that much. Without it, the spirit of the narrative is diminished. The essence has changed. There are particular details and scenes in a book that, if left out, the whole thing becomes a completely different story, or a character becomes a different person entirely.
If you cook the shrimp, it is no longer ceviche. You can ask for steak tartare well-done, but then it isn’t steak tartare.
To go back to our Harry Potter examples, the sixth movie, Half-blood Prince, commits such an act of vandalism.