I can see why poeple would think Jujutsu Kaisen is garbage, and I really don't blame them. The beginning of the manga is so generic, so cliche'd, that I myself almost dropped it by chapter 10. That being said, if you stay around long enough, it gets better.

Let me talk about the absolutely garbage beginning. Our "plebian, normal" protagonist gets thrown into a "supernatural hidden world!" Wow, never heard of that before. He takes the plunge into the world and sacrifices himself in order to save his likewise plebian friends from an evil curse, but gets saved by a passing by a good curse practitioner, who then brings our lovely protagonist into his protection. Soon later, our curse practitioner friend is hurt! Our protagonist has no choice but to consume the evil curse's power, thus bringing him onto the brink of insanity, but he survives in the end, gaining "one of a kind" powers. He also shares his body with the evil curse spirit that he consumed, who happens to also be one of the most powerful curse spirits in the world, it's just that he's in a sealed state! Higherups in the curse organization think he's a source of danger for consuming an extremely powerful cursde make an "exception" to make our protagonist a licensed curse practitioner, where he gains new friends, and fights evil curses for justice!!!! I feel like this beginning was just a challenge to how many tropes you can put into one story. It's terrible. The plot is straight out of the 1980s generic shounen garbage pile.

However, it DOES get better with time. Story arcs actually become interesting, thus making it actually engaging, and characters of all sorts get fleshed out, characterized, and the manga does a great job with doing these things, especially the characterization. You get to peer into a characters' heart and past, allowing you to actually feel more about them than just "generic character A." Stories about these events are pretty interesting. The enemy encounters are also great. High level cursed spirits are intelligent, thus conversations, personalities, and strategies all clash and create a great story. The protagonist, in the end, is just your generic MC with plot armor. About to die? No problem, just bring out the OP evil spirit that's inside of you and kill the enemy and survive. This happens a lot, by the way. But the thing that I like about this manga (at ch 126 anyway) is that there is not a lot of emphasis on our MC, and a lot of more interesting side characters take center stage, which actually have a personality and have chances of dying. I think that the manga does a great job of actually having certain characters dying, unlike in other shounen, where somehow everyone manages to live. In this series? No, people will die after intense fights, and this is definitely a good thing. It's not too infrequent that there are no consequences, and not too frequent that everyone you know is dead. It's a delicate balance.

Another thing to point out that I quite like a lot is the way cursed power is explained. Everyone knows the idea behind "spiritual energy," but this manga creates a unique system for it. People's powers are very well made and interesting to explore, both the cursed spirits, and the curse practitioners. Fights between these characters with different ideologies and cursed energy manipulation makes each fight stay very fresh and keeps you on your toes. Everyone is constantly innovating their craft, and creating new abilities to counter others or to destroy them, and there are many strategies to make use of each person's ability to their fullest ability. It's like One Piece, where everyone has their devil fruit powers that are unique to them. Plus, there are some cool concepts that are universal to all cursed energy practitioners, like the "field." I won't spoil anything, but there are some common ways every user has to manipulate their cursed energy and fight in their own "zone," so to speak.
Art is pretty good. I like the fights in the manga, and there are a lot of those, so no complaints there at all.
Despite the fact that the manga gets better, the beginning chapters are terrible, the MC is extremely generic (personality wise), and the MC has god-like plot armor. So no, it's not a masterpiece, but I'll tentatively put it at a 7/10 for now.