To be honest, when I first heard that Trixie would be returning, my first thought was "Oh crap. This is where it drifts into mindless fanservice." but I was thankfully very wrong. A solid episode, for sure. Sure, the plot is one that has appeared in many other things (humiliated villain finds new source of power, returns for revenge), but it works, so I'm not gonna complain. It's a show about cartoon ponies.
I think this episode could be a good, new direction for the series. Continuity doesn't hurt, right? Plus, I actually liked seeing a villain do something, unlike a certain villain.
And we got some more Pinkie Pie breaking the fourth wall moments, too. Oh and ZECORA :D