When I started watching the show the episodes were funny at first, but it got repetitive pretty fast after the main characters were introduced. The story and the character development slows down and the episodes are the same thing over and over again. (could be filler though)
I even dropped the anime for a while. But I kept reading stories about how it gets better in later episodes, and it did!
Hitman Reborn is a pretty unique anime in my opinion. There is one major flaw in the story that prevents me from giving it a full 10. The first 20 episodes or so have no real story arc. While each episode is interesting and helps develop the characters it takes way too long for the story to truly begin.