(spoilers)
This has definitely become one of my favorite episodes of all. As I've said before, time travel has always fascinated me, and I really liked seeing all the alternate futures that were being created with each loop to the past. And at the end of it all, there is now ultimately almost no major changes to the show, aside from possibly a new character to the cast in the form of Starlight Glimmer. Not since season 1 or 2 has there been a finale that stuck so close to the status quo. (Season 3 had Twilight become an alicorn, and season 4 had the library destroyed and a new castle created, though considering that at the start of season 3 we had the sudden return of the Crystal Empire, I'm tempted to say that it was only between seasons 1 and 2 that things mostly stayed the same, so we'll see if that'll be the case once season 6 starts.)
Speaking of Starlight, I'm honestly quite surprised that there's so much hatred for her here. Even though I kind of expected her to ultimately end up reformed, I actually like this. I suppose every season finale lately seems to come with a big controversy: alicorn Twilight after season 3, the loss of Golden Oak Library after season 4, and now Starlight's reformation in season 5. I had accepted the big changes of the previous seasons, and I will still do the same for this one.
To be honest, I actually see a lot in common between Starlight Glimmer and Sunset Shimmer. Both of them once had evil intentions, but thanks to the actions of Princess Twilight, they have both been shown that there was a better way. (In fact, near the end of this episode when Starlight hesitantly accepted Twilight's hoof in friendship, I was immediately reminded of the ending of Friendship Games, when human Twilight hesitantly accepted Sunset's hand in friendship.) I recall that it wasn't until after Rainbow Rocks when people started to appreciate Sunset Shimmer as more than just a former bad guy, so I'm confident that, given enough time, fans will warm up to Starlight Glimmer as well.
(end spoilers)