It had a good story, though lots of things I could compare to Naruto, sadly (I never enjoyed Naruto) and because of all these similarities, it seemed less original. I could brush it off with the "same inspiration" excuse though. Now let's review...
I loved the story... to a point. I could do without a few things, but other than that it was fine. The way it was executed sometimes though, was badly done. Also, again, many similarities with Naruto.
Art was the same/close to Naruto's, but once again, "same inspiration" excuse was used for my enjoyment of this series to continue. I also don't think that Naruto and 666 Satan's is the best/greatest, many other works are ten times better.
Characters... some I liked, some I didn't. I disliked Ruby and Mei, same with other females that made me ashamed to be female. The characters weren't always chivalrous, and rash, which made me like the characters more (the stupid, brave, and strong characters annoy me after a time), but then again, some were like that.
I also want to point out, the ending wasn't as bad as people were saying... it just wasn't the usual "happy ending" that many prefer to have. Although it wasn't exactly the best way to end the series though... all in all, it was good, I enjoyed it.
This series deserves a 7.5, because even though it was a great story, it wasn't executed well, the characters weren't all original, and throughout the series, I always inadvertently compared it to Naruto.

Enjoyable enough, perhaps a little above 'medicore' but seriously, not much.

Characters are ... shounen-y, powers and fights can be quite interesting, but still pretty ...shounen-y.

It's another one of those DragonBall (not DBZ) inspired manga, as in it took actual parts of DragonBall's training arcs and shamelessly plonked them in.

Incidentally, all the Naruto comparisons are for these reasons:

1. The two mangaka are twin brothers (which goes a long way to explain why they're so similar).
2. Naruto has a demon fox sealed inside him, Jio Freed has Satan sealed inside him.
3. Ambitions - Naruto wants to become the next and greatest of the Hokages, Jio wants to conquer the world .
4. Art style is very similar.
5. Antagonists who want to capture/control all the demons/angels (666Satan) or Tailed Beasts (Naruto) to attain their goal. Which is also rather similar in nature.

However, they are quite different manga, and Naruto manages to be better for actually kicking ass more consistently. Of course it has its flaws (it's called Sasuke ) and for not being completely formulaic all the time. We've yet to see if the ending will please of course, let's hope Kishimoto Masashi does not have his brother's taste for endings (slightly off-topic spiel over).

Read it if you're bored essentially. Enjoyable enough to give it a go, but don't expect to be surprised, this is a standard shounen through and through.

... Last updated on August 29th, 2013, 2:11am

well,you can call this to have weak plot,etc. I can never understand people who complain about the structure of the story.

but that's not how i judge a book/manga, i judge whether this can hook me up and makes me excited
that's what i call good story. and this manga does just that very thing ( and older jio looks better than naruto)

I must say that this manga is better than naruto, I liked Jio better than Naruto, Naruto is just.....
let's just say I want to throw naruto off into the abyss (he struck my nerve and many other reason)

I throughly enjoyed this manga, the ending is ok, but what's important is how it reach the ending.

For a lot of the series it is entertaining enough to keep following, but in the long run the story is just a little to weak to really fall in love with. It's a good manga to start with, but for those of us who have matured past the Narutos and DBZs this will in a sense just be too childish.

i was interested at first because the main character looked like my oc when I was a kid...but the story is plain boring..i don't feel anything coming from this manga and the reason pushing the character are shallow..the art look like the one in naruto and part of the story as well (maybe because those two are brother) but i don't like naruto too bad..but I still prefer this one over n.

Let's start at the beginning. The Very first chapter of this manga was a bit of a put off because the structure of the chapter itself was stereotypical and milked to death. It does fairly well at introducing the manga but anyone who is looking for a good manga by randomly sampling is going to be put off.
The story progression is fairly linear with mid length arcs but with not much in terms of the plot. The character growth is constant throughout the story but with the concept of the powers incorporated, the power growth is fairly limited. The timeskip roughly two thirds into the story serves only to complicate matters as all problems related to it disappear within a matter of pages. The story from there on out is predictable and boring, in contrast to the first half which was at least kind of random.
The characters themselves are nothing new with the exception of Ball. Jio, Ruby, Cross, Kirin... I feel like i have seen their precursors in many other mangas. This can't be helped in most cases just in terms of the overused plot of sealed demons with the strongest within the main character as well as other not-quite-as-strong demons/angels in other less important characters.
The ending, as others have remarked, is a bit disappointing, not because there were gaping holes but the fact that you have no idea why the characters would do such a thing. The characters seem so content with their absurd reality that you have to laugh at their stupidity (the only funny moment in the story).
That said, its really not that bad a read, provided you have nothing else to read and are either ten years old or your brain is in outer space or somewhere else it shouldn't be.

It has potential if he had taken care of it more and developed it.
its sad how people keep comparing this manga with his brothers naruto.
this has a unquie plot the drawlings become better as the story progresses. The ending was rushed you can tell he wanted to end it. It's worth a read but, when you read it you should forget about naruto and just read and enjoy if you know what I mean. it can be cliche at parts but its good it's too bad most people just don't appreciate because it's not better than naruto (so they say...) It's worth a read.. it's still stuck in my head after all these years haha.

... Last updated on January 14th, 2010, 5:46pm

This was an interesting manga that just evolved into a very boring and random storyline quickly. guess all those hate mail he recieved just forced him to end the manga quickly after the supposed "copied" timeskip. It's still no excuse though.The rushed ending was just pathetic. Otherwise it has many elements just like Naruto. yeah. Pretty boring to read unless you're a fangirl or childish boy that likes manga with just "interesting characters"<<<?? or cliched ones with a very random storyline with no foreshadows like naruto. AND yeah thats the end of this review.

... Last updated on August 1st, 2009, 3:52am

I don't know why some people gave this series such a bad rating. Yeah, there's cliches but what shounen DOSEN'T have some? Also, people are comparing it to Naruto just because the mangaka are siblings, and all the copying accusations, and saying "oh this is a naruto wannabe" blah blah blah, but really, what do you expect when they are freakin twins? I love this manga and in my opinion, it is set in a completely different theme than Naruto. It's good, but of course Naruto is better. Great read especially for Naruto fans!

somehow I found the ending bitter sweet :/.... I like the endings where you can be sure of urself. But in this case I can't think of a better ending to suit it. I can't really bring myself to dislike the story, but I can't say I like the ending.