To me, it's like watching the same thing over and over again. The plot lines in the episodes that I have seen have been done to death like "I am being embarrassed by my quirky relatives behavior only to finding out that they are actually pretty cool" or "pretending I'm not to be friends with my friend in order to be with the popular/sophisticated people only to realize that my real friends are more important." Other shows manage to make these plot line interesting with humor, drama, or creativity, but for me, I have trouble seeing any of these qualities in MLP and instead feel that it boils down the over used stories to their basic elements, which is perfect for small children but dull for me. I don't think it's a bad show, but I don't see why it's so special either.
I like the show, used to be part of the fandom, grew out of that real quickly. I'm trying to get back in, but keep failing to get into it like I did in the season one days. I still watch the show, but that is it.