Finally got around to reading this after trying the first chapter when it came out and I really like it. It feels very different to a typical Jump series, which is kind of nice. Though the idea of the Fire Punch author writing a Jump series is kind of crazy, but he has done a good job balancing the things he is known for, like extreme violence and bizarre situations, with what he is allowed to do in Jump. The recent chapter and Denji's battle with the eternal devil being examples of this. Also Denji's character as a lead is interesting too. He kind of reminds me of an Ikki from AG or other Oh Great characters with his dumbness and his simple "motivations" for things, but clearly being a good guy overall despite the rough edges. You don't see too many MCs like that. Although Power might be my favorite just for those scenes where she tries to lie or acts like a child with her ideas of getting what she wants, haha.
Also I really like how the world is being built. The devils' power being based on fear is interesting. Like how guns are obviously very scary so the Gun Devil is incredibly powerful, but like a shoe devil would be kind of weak. There is a lot of things you can do with that as an idea. Like a devil based off darkness, thunder/lightning, public speaking, or other big fears creating strong devils.
As for the new chapter I really don't know what to think. Fire Punch makes me think that there will be more than typical twist with Makima just being alive. Obviously she has an important role in the series given how much of Denji's motivation is built around her, as well as Aki having some deeper connection to her too, so I don't think she is gone for good but I can see this "version" of Makima being dead or she will have some very unexpected ability that helps her here. You figure she has some powerful contract with a devil given how scared Power is of her, but I don't know.