I've practically written… dissertations on why Reborn is awful over in the Reborn thread. I'll just rip one from over there (thanks Kareem!):
Reborn is an abomination. I've read a LOT of manga of all kinds, and even in terrible ones I can find something to enjoy. But the only way I think Reborn could be worse is if it was a harem manga with loli pantyshots. Hibari and Yamamoto are the only redeeming features of this manga.
Other bad manga, even Naruto (usually), take the time to set up and establish the absolute bare bones of the fighting system. In One Piece, you'll see Devil Fruits. You know well what their strengths and weaknesses are, or at least that there's a power out there somewhere to counter it. You know what to expect from the three types of Devil Fruits. In Naruto, there's chakra, 5 elements, and ninjutsu, genjutsu, and taijutsu, each with their own checks and balances to each other. In Hunter X Hunter, you have what is probably the best chakra system in all of shounen, in the form of Nen, which is extremely creative, extremely balanced, extremely complicated but at the same time makes perfect sense. There is a world, and when things happen in that world, there's at least some level of consistency within that world.
I'm not sure whether I would agree that Reborn is worse than Bleach, but I would probably agree that it's at least as bad. Having started out as a gag manga for the first 60 chapters, Reborn went the route of becoming a battle manga, but unlike in all the other shonen series - it didn't have the benefit of all those chapters of establishment while you're still learning about the world. It just shoehorned things in. In many ways, it introduces plot points like Naruto part 2 does. Outta the fucking blue.
So as a series, it lacks a lot of very basic building blocks and when you look at it, you see a lot of holes.
What's worse, because the whole fighting system is sort of winged, battles become less about who fights the smartest or uses their ability to the utmost, but a complete writing crapshoot. The strongest characters will (literally) run into a brick wall (literally) and lose battles with no build-up. A fight could last 2 chapters or 6, and then a character (usually one of the protagonists) will inexplicably take a dive. In Naruto, you know shit is getting real when Naruto goes Kyuubi. Gear 2 means it's on, with Luffy. But in Reborn, a character using his latest power-up (and there's one at least every arc) will lose just as easily as if he hadn't at all - it's frustrating, and disjointed - and not at all unlike the war arc in Bleach.
As a battle manga, it fails completely. Sadly, it isn't funny either: its concept of humor consisting of an [extremely annoying] baby making fart and poop jokes.
The writing is just really bad. Unavoidably. It's not as bad as, say, Air Gear, but it wants to be. You can count the fights that have included more than 3 participants on one hand, but rarely are characters really indisposed, so you'll have an entire cast standing around providing extremely basic exposition for every fight and hammering you over the head with symbolism over and over and over again. Reborn! has no concept of "Show, Don't Tell," and so it is consistently unconvincing. Like remember how in Bleach, Kubo made a point of having Aizen predict everything down to what someone had for breakfast that morning? Know how it got to the point where plausible deniability went soaring out the window and no matter what was being written, you just couldn't believe it was being shilled as the truth because it was just too absurd? It's like that - only all day every day here in Reborn country.
Characters say, "Gokudera-kun is so reliable desu" while your mind is shouting "bullshit!" because the character has literally won 2 fights and lost or pulled a draw in something in the neighborhood of 15 (not kidding). You may say to yourself "well it's good that the good guys lose sometimes, that doesn't happen often in other manga" but not so here, because even though more than half of the main cast is terrible 90% of the time, contrived plot twists and limp-dick writing always lead to the good guys winning and rainbows and sunny skies and fart jokes.
Characters don't develop, Tsuna is probably the worst shonen protagonist I've ever read, and I've read a lot. He's everything that was ever conceivably bad about Usopp, whiny, and so constantly surprised you might think he was wandering through life on LSD.
All this may seem a bit extreme to you. Maybe it is, idk. But I really haven't even broken it down yet. I haven't even TALKED about the absolutely random pokemon battles involving genjutsu sea slugs that were added to give "spice" to the plot. I haven't even TALKED about the Time Travel Ten Years Into the Future arc.
If anything, my vehemence is a desperate plea for you to listen to the hyperbole for once, listen to the people who are trying to spare you the pain, just find a different mark, just find a different quarry.
This manga aspires to do interesting things but bungles them all, resulting in a shounen where everything is half-assed and the other half is just ass.
Stay away.
tl;dr version: horrible fights, wretched, useless characters (including the most deliberately obnoxious character any manga I've read [he-who-will-not-be-named]), plotted like naruto p.2, only one or two good arcs in the entire series, potty humor, subtle-as-a-brick writing.
good points are character designs (sort of), and anyone who actually ACTS like a mafioso, which is to say Xanxus, Squallo, Hibari, Yamamoto, and Reborn himself.
It's just, really, really bad at everything it tries to do. BUT IT'S GOT PRETTY BOYS SO IT'S HERE TO STAY uguu~ :wub: