Helck is literally the most fun I ever had with fiction.
It doesn't sound like anything particular innovative, and it isn't really, the Demon King was defeated and they're holding a tournament to choose the next one, does the twist that the guy who killed him is in the tournament and goes around with a funny face saying that he hates humans makes it more interesting? Of course it does.
Helck has a lot more comedy in the early part than the rest, i'm not going to pretend it's a series that "starts childish but get serious" or anything, it's just a series that happens to mix stupid comedy with interesting twists to plots we have seen before.
But, if that's the case, then why did I gave it a 10?
Because it's freaking amazing.
Even tho Helck's name is in the title, almost the entire manga is presented to us from Vamirio's POV, she's may seen like just a tsundere, but she's actually really likeable and cautious, since we follow her trying to discover the truth about Helck, it allows us to see not only Vamirio's character better, but also makes Helck's past more powerful, i didn't expected this series to give me the strong emotions it did, but i understand that because the series relies so much in her, a lot of people might not enjoy it that much, i also feel that the author understood this and porposefully made the first arc more comedy-heavy.
Big gentle guy and small angry demon girl are a lot of fun to follow.
I noticed the artwork getting significantly better as the series goes on, i also think that this has the best usage of lightning in shot composition i have ever seen, not just black or white backgrounds, the character design is also really good.
If you feel like Helck's strength is going to make it not fun to read because he will punch his way through everything, keep in mind that Vamirio is almost the protagonist of the series and that characters like Azudora have fights that are a lot more detailed than Helck's, and honestly even tho i would enjoy more tecnical fights, the fact that the strength of those characters is actually a plot line and not just a gag makes me forgive it easily. Also, having such insanely powerful punches makes up for some incredibly well executed scenes later on.
If you're going to read Helck, i can guarantee you'll laugh a lot, and save some of the pages because you want to look at then for the rest of the day, but unless you find yourself so invested in Vamirio's character as i was, then this will probably just be a entertaining series for you.