personally I love the show and the reason isn't hard to understand, you just have to give it a chance.
the reason I love the show is because it is vastly different than 90% of the cartoons out there. the characters are well written, in fact the show is so character heavy that unless you know the characters you won't get any of the humor.
the creator is known for doing this. she was the creator of the Powerpuff girls and fosters home for imaginary friends. she writes for not only children, but adults. she puts in smart refrences that only people in their 20's/30's will get (the number 42 for instance, she used that as character humor and not just a refrence.... that is how well the show is written).
it's just refreshing to see a cartoon not treat children/adults as morons. and the show has absolutely nothing to do with the previous shows, in fact the only reason they are ponies seems to be to make horribly awesome pony puns, other than that it doesn't matter one way or another.
all hail the crimson king