Katekyo Hitman Reborn is a shounen about Tsuna, a no good loser from japan. Until he is visited by Reborn, a hitman home tutor from the vongola family. Together with Reborn tsuna must train to become the next mafia boss of the vongola.
Hitman Reborn has a fairly slow start but once the second arc begins you wont be able to stop watching.
The characters unfortunately is where the show falls down. All the characters are predictable with one or two exceptions and some characters become useless and annoying towards the later parts of the manga.
The artwork is quite good, the the attacks look awesome and emotional moments draw you in.
Overall I would recommend this manga to any shounen lovers and generally manga readers.