In KH2 he can finish a character off really quick. I think the first Sephiroth was a bit easier, although you have quick reflexes, high level, and know both your moves and his moves and time them exactly right. Otherwise yeah he can be a pain. When I first played it I didn't know he would appear either, I just sat there watching as the music rolled and Sephiroth beat Sora over and over(I sometimes would just go there to watch what moves Sephiroth would use, he usually has a pattern). Although you need patience it's still fun.