Not only do these folks know the TV show well, but they also created a system that is really good. Everything is rated by a die type, and you have to roll a target number or higher (2-20). The book is easy to read, and easy to understand (my 8 year old read the whole thing with no problems). The system and the adventures have both adult and kids apeal to it.
The only things that are negative is that I think they have too many target numbers. They should have less numbers. I understand why you would want to include a d20, but it's quite a jump between a d12 and d20, so I woiuld have just left them out (but it's not an deal breaker by far).
They also wasted a lot of pages on random number pages at the end of the book. These are in case you don't have any dice... but I'm pretty sure that if you were able to get ahold of this book, then the place you ordered it from has dice. So, it was just wasted space.
I'm hoping this game stays on the market, because the other MLP rpg coming out looks like it's aimed more at adults with that system that does not look kid friendly.