Aw, I liked today's episode. It was nice to see Twilight again, and I liked seeing how she caused herself to get hurt to appear the way she did in the future. I also liked the lesson, since it's one that Twilight (and I) really need to learn.
I do hope that there's more mentions of Tartarus in the show. Fascinating to know that Ponyville is close enough to the gate to the Greek underworld that it's a simple enough trip Twilight didn't have to pack for it.
Also hope there's more use of time travel in the show. There's so many ways now Twilight can play with either the past or to prevent the future that it would be a shame for her to never time travel again.