This was... A mess.
I already had low hopes because, while JJK had a strong start and a weak finish, this didn't even have a very strong opening. But this wasn't just unbelievably mid, it straight-up got so confusing at the end that I had no idea what really happened. I should probably take this apart piece-by-piece to get a better hold of things.
The characters: They were fine. They all felt like diet-versions of the OG JJK cast, but they weren't terrible. Yuka had so much promise as a Yuji/Nobara character, but once again Gege shafted her by giving her a terminal illness and having her summon Mahoraga to fight her greatest battle. I assumed she would have been the main character, but it really quickly turns out that the main characters are the alien twins. Next is her brother whose name I had to look up because he left such a small impact on me. Tsurugi is more a combination of Maki and Fushiguro than anyone else. He read early on like he was going to be a rival character. He and Yuka would be completing missions and butting heads, all while being a fan-favorite that I personally found boring. Instead he's an empty character with two overpowered abilities (directly inherited from his parents), and doesn't SEEM to have much semblance on the plot. Then are the two TRUE main characters: Maru and Cross. Cross is just Tsurugi but even more boring, and Maru is a kind young lad who seems to be driving the plot and themes forward more than the rest. He is, like, the only character I cared about after Yuka was booted from the manga.
Next is Artwork. This, I can say, is still pretty alright. Nothing groundbreaking, the action was admittely pretty mid, but it's not like it's an "Ugly" manga. Far from excellent, but not bad by any means.
Lastly is... story. The story was the worst part. Everybody's made the joke, "They took JJK and added DanDaDan to it", but it really illustrates just how out-of-nowhere the shift in worldbuilding is, and how it very much feels like chasing trends instead of following on pre-established story elements. Having alien refugees trying to find a new and healthy homeworld in Earth seems like it could be a good idea for its own story, but adding it to Jujutsu Kaisen is one of the most peculiar story additions possible. The worst part? This ISN'T the worst aspect of the story. It's just the most jarring one. Even if we take this story in a vacuum (which is difficult because it keeps reminding us parts of JJK proper), it's just got a bunch of meaningless twists-and-turns. Story details get added then dropped, characters have a hair-trigger and seemingly WANT conflict, and the power scaling shoots so far up that it's almost incomparable to the original series. And at the end? A character I believed to be dead comes back to life for no reason, teams up with a lead from the last series, and fixes EVERYTHING. And, like... I don't even know how they did it. They explain their plan over the span of 2-3 chapters, and I STILL don't know how they fixed it all. I don't consume a lot of media (it's why I started this page, so I had a reason to watch/read more stuff); so this might just be one of the first time that I, personally have experienced a Deus-Ex Machina. It's just so confusing that I was left completely unsatisfied.
It's not the worst thing I've ever read. It's a massive disappointment, I can say that much; but it's far from utter gutter trash. So I guess... I can give it a 4/10. I felt no enjoyment reading this, but it didn't make me actively upset.