For me it is the many different emotions that it puts me through. I often cried because of these sad scenes, then laughed my ass off a moment later, when something silly and fully out of place happened. And I love the characters, almost all of them. They are adorable and they totally rock. I only really hated Danzou and disliked Konohamaru and Jiraiya but the rest I adore. I love seeing what they all do and how they act. Plus it's constantly exciting.