Why the show is worth watching:
The animation is great, and the script is well-written and hilarious. The characters all have their own traits and flaws, and the interactions between them lead to some hilarious shenanigans. You can tell the creators of the show put some real effort into it, and actally wanted to make something awesome.
What I think MLP has to offer us as a society:
You don't often see that kind of effort from the creators with "girls shows". Usually the shows aimed at girls are, for lack of a better word, dumb. Producers often figure that colouring everything pink and adhering to "girly" plots and characters will sell the show. And then when they get bad ratings they conclude that girls don't watch TV. Except it's likely that girls DO watch TV... they're just watching the boys' shows.
MLP really breaks away from conventional stereotypes, in that it's something that can be enjoyed by everyone. The Powerpuff Girls is another show that did the same thing... "Girly" subject, but universally funny execution. It helps break the notion that "girly" stuff is automatically lame. The show has changed a lot of people's perspectives. Liking ponies is no longer a sign of weakness... because ponies are awesome.