Personally, I have mixed feelings on that matter. There is no denying that it's good entertainment (provided, you aren't turned off by style), but is it teaching good morals? For the most part I think so, however, I do remember seeing few, shall I say, not very good messages or at least the ones that could be interpreted wrong way. Of course, it's not like it never happened to other shows for kids. Still, I do recall seeing some of them and cringing quite badly.
At the moment, I can't really judge as I simply don't remember exact examples. However, I am working on the review series for MLP, so I guess I'll be more capable of answering in the future.