I think the appeal to it is the overall story that most people started watching from season 1 or season 2. If you just jump in I can see how you thought it was slow and, some episodes are infact slow but, those are the ones that is developing the character's story. Another thing is once you start to get attached to a character they usually die and you're like ohhh nooo. In short it's something you have to watch from the beginning.