It's clear that the author didn't planned the series to go as far as it went, the first several chapters present a mostly slice of life manga focused on comedy, but eventually the author realizes that it's a Jump title, so BOOYAH! here comes some bad fighting arcs, from here all the way to the end, with a tinge of badly written science fiction.
The problem with this series is repetition, which is not an abnormal thing when it comes to Jump titles, but it's just too damn much. The last arc, which was supposed to answer questions about some of the biggest mysteries of the manga, is just a mess of a tournament arc with lots and lots of fanservice and barely any plot.
On that point, KHR barely has any plot or character development, even though some characters like Gokudera and Yamamoto have interesting backgrounds and ideals, most of it just gets drowned in pointless fighting or repetitive comedy chapters. Every single potential development is wasted: some characters are interesting, the art is great, but everything goes down the drain because we surely need Tsuna to get new gloves and fight people he doesn't want to fight but he does so anyway since, you guessed it, it's Jump.
This is not good. Watch the anime up until the end of the Varia Arc, it's way more pleasant than reading to the whole manga series.
(To be clear: it's not a problem to be a Jump title or use shonen manga cliché. The good part about Jump manga is what authors do within those clichés to set themselves apart. KHR barely tries and clearly failed.)
