I was a huge MLP fan as a kid in the 80's. I had just about every pony that came out from 1983-1987. I was resistant to the new MLP series, as I really didn't like the new designs. The stories however won me over. They are well-written and not sappy like the original MLP series in the late 1980's. I tried watching the original series (which I had loved) a couple of years ago, and barely got through one episode.
I also like that in the new series they are not afraid to go off-model. There are zebras, mules, and in one episode I saw, a body-building pegasus! Too funny!