Don't expect a pro review from me, I'm just a guy who decided to give his two-cents on what he thought from what he read. I've read up to ch. 24 so this review will be based on that progress.
Writing Quality: 4/5 - It's good but there's frequently some issues that pop up that make me have to re-read some passages. Just minor things or at least I thought they were. Other than that, I didn't really spot much else.
Stability of Updates: 4/5 - I came into this novel when there were already 24 chapters available so I feel it'd be unfair to give a better score here. Though I did look at the release dates and they seem to be released on a 1 chapter per day frequency, so it's got that going for it.
Story Development: 3/5 - Let me just say real quick, I'm loving the premise of the story so far, Superman in One Piece world. With that said, the story itself feels very ... I can't say fast or rushed cause that wouldn't be true. A story IS there, but it feels very 'bare bones' but enough to not starve, if that makes sense? Let me try again, imagine a pizza in front of you (if you don't like pizza, then I'm sorry but I'm still gonna use it for this example) but it consists of nothing but the dough and a little sprinkling of sauce and cheese toppings, not enough sauce and cheese to actually cover the pizza, but just enough to give it 'spots'. Now this pizza when cooked will still fill your stomach just fine and all, but ... was it truly satisfying all the needs you seek from a pizza? It missed all those small details, it failed to expound on moments that needed it. Now here's the crazy thing, the baker of this pizza HAS all the ingredients necessary to make a satisfactory pizza, but they choose not to or maybe they don't exactly choose to do that specifically, but regardless a choice IS being made to not add those extra needed details.
Character Design: 4/5 - The characters make sense. The MC (his name is Nova) feels believable with his actions... or at least most of his choices but that's fine.
World Background: 4/5 - There was a moment or two where I had to go, "Reeeaaally?" So I don't feel it's perfect, but it's still good.
Overview: So the quick and short, is this novel worth your time? Uhh... maybe? Yeah? I mean, if you're a Superman fan, then sure go for it. If you're a One Piece fan, then sure go for it. For everyone else, give it a shot, it won't take that long to read to ch. 20 (the chapters aren't that long) so make your opinion then, or sooner, your choice. I would honestly advise that the Author start taking their time with adding and/or taking their time with the small details. Contrary to what I may be sounding like, I actually DO like this novel and plan to continue to read it. I would love to see the author improve as the novel progresses. I'll edit this review as this novel reaches higher chapters. Oh yeah, almost forgot, the author also stated that the novel is planned to be non-harem (so far). No sort of romance has started yet.