Skeleton Double sucks. Oh, you want to know why? Sure, I'll let you in. (Minimal spoilers ahead) There are two major issues with Skelly Double. First, the ending is bad. It’s the classic "Shit, I've run out of chapters, let me just wrap this up". This probably isn't the mangaka's fault, but it still makes the manga worse. The bigger issue is the second. It's faux-dark, or for those who aren't pretentious, it fakes being a dark story. Skelly Double's aesthetic is dark, after all the main superpower is skeleton/blood based, but its essence isn't. Allied characters don't die, the main character is nevertruly challenged. Bad things might happen, but it’s never to our main cast (unless its in the character's backstory). For all its flaws, Jujutsu Kaisen is an example of story that is willing to be dark. Curses kill and destroy, and JJK's main character has to fight and survive their darkness. Sometimes he saves the day, sometimes he doesn't. But Skelly Double isn't committed to its darkness. Sure, a group of characters go on a mass killing, but none of the main cast suffer this. The bad guys can't kill a single good guy, just random civilians we've never met. Even when one of the baddies gets super charged by the plot maguffin, he's still so worthless he can't kill a single relevant character. Whats the point of having a dark aesthetic without actual darkness? If you wanted to make a hopeful shounen, you should've just made one.

Skeleton Double has interesting elements, but it fails to do anything meaningful with them. It never goes beyond its potential, and in the end it achieves nothing.