I'm a Brony, so I'll try to answer this. The most important part is the plot. All episodes have a conclusion and this is very rare in shows at this time. The second thing is what says the title itself - "Friendship is Magic". Friendship is important, but we forget about it more and more often. MLP shows, how important is the friendship. The plot actually makes sense, not like in other shows of this category. For example, there is a show called... Teletubbies and when I saw a fragment of one of the episodes I felt like my brain was about to explode, because it's nearly the stupidest thing ever. MLP is very different. It is interesting. There is also action, some really dangerous victims, not everything goes easily, sometimes the main characters are very close to losing. If you ripped it off of the candy animation style, you wold see that it's a deep story about friendship that lasts despite everything.