Galerians: Rion is kind of a mess, but largely because the original Galerians (a PS1 survival horror game of which this is an adaptation) is also largely a mess. It seemingly uses the same engine for in-game cutscenes, meaning the entire movie kind of looks like a PS2 cutscene. It expands upon scenes while largely keeping the plot and beats the same, which does include the final twist (which is presented as "maybe a lie maybe it's true" but no matter what you'll have to swallow some pretty massive plot holes either way). If there is something that Galerians: Rion directly improves on the originalover, it's the voice acting. The voice direction is much better (as opposed to before where it was nonexistent), and while Rion is supposed to be 14/16 but sounds like he's 20, it is probably better than when he sounded 10 and mumbled a lot.

So why the high rating? Because I'm approaching this from the perspective of a fan of the original Galerians. And if you really enjoyed the original game in spite of its jank, you will most likely find the movie to be pretty cool. The oppressive and freaky environments are realized in full 3D space. The villains generally appear earlier than they're supposed to, giving them much-needed foreshadowing and more time to appreciate their character. And the fight scenes, while they suffer a bit from "DBZ screaming and glowing until the other guy's head explodes" syndrome, do convey more dynamism and how terrifyingly powerful a Galerian is supposed to be than the game does sometimes (though Shorting doesn't feel as great, admittedly). And if you're enough of a freak to actually like Galerians, then the fact that the movie is an hour-long PS2 cutscene isn't even a negative.

The fact that Galerians is already "we have AKIRA/Scanners/Parasite Eve at home" makes it redundant when taken outside the context of a game, and as an anime I think it probably fails to stand up on its own merits. But I think its strongest points are that it might interest newcomers into getting into Galerians, and for pre-existing fans it serves as a re-imagining of the game. I probably won't watch it ever again, but I think it is interesting, and maybe that's what matters most.