With all the teasers and trailers and spoilers flying around, I'm really glad that I managed to watch this episode without knowing ANYTHING about it at all save for its title. Kudos to everyone: the official folks (Hasbro, The Hub, DHX etc.), the "big names" in the brony community (especially Equestria Daily, who scrupulously avoided dropping any spoilers on those seeking to avoid them), and of course to every brony who avoided spilling the beans.
Two songs this time; oh, I've missed those. There was a longer one in the first part, featuring ALL the princesses: not just Twilight but also Celestia, Luna and Cadance. I don't think we've seen the latter two sing yet, have we? Certainly hoping it won't have been the last time. Quite a beautiful song as well, in any case, and in the second part, there was also shorter one featuring all the Mane Six. Daniel Ingram — kudos for a job well done, again!
We got a new villain,
As for Tirek — I couldn't help but wonder, just what IS he? (Initially, he looked baboonish; later on he was revealed to be more of a centaur.) And what, for that matter, is his motivation — why is he keen on amassing power and sowing destruction? Some MLP:FiM villains have been criticized for being – well – shallow, Sombra being a notable example. Of course, I think that Sombra was planned as an ominous, threatening presence, akin to Sauron in the Lord of the Rings; whether that worked as planned is a question I don't intend to go into here, but like Sombra, Tirek appeared to be evil solely for the sake of being evil. I prefer antagonists who're not just simply villains: ones like Night Mare Moon (driven mad by loneliness, neglect and jealousy), Discord (living embodiment of chaos), and Chrysalis (queen of a swarm that she had a duty to protect and feed). It makes for much more interesting characters, especially when their reasons are understandable and relatable (e.g. NMM) and/or when they're morally ambiguous to begin with, shades of gray rather than black-and-white, good-vs.-evil (Chrysalis, whose methods were wrong, even cruel, but whose goals were ultimately understandable). Well, maybe we'll learn more about Tirek and his motivations eventually.
Speaking of Discord, BTW: he played a key role in this episode (no pun intended), and a two-fold one at that. First he provided the crucial hint on how to unlock the box that the Tree of Harmony had produced way back at the beginning of the season; and after betraying the ponies, he ultimately ended up providing the last key as well. I think he also learned a real lesson here, and seeing how much interest he took in the Mane Six's diary here, perhaps HE will write an entry in it now. It sure would behoove him (again no pun intended). On a side note, when he accepted Tirek's offer, I actually thought he was playing a double game: pretending to go along with Tirek's plan while secretly sabotaging it. But Tirek's silver tongue really got to him, it seems.
All the Mane Six and Spike played a role in this episode, but obviously Twilight was the one at the center, the focus of the episode, the one who really shone. Her existential crisis was very relatable, and I was overjoyed when she finally found her purpose: and note how she chose it of her own volition, too. Your destiny is not set in stone; you are the master of your fate, you are the captain of your soul. I think that's an important lesson to learn (again).
Twilight's library being burned down was unexpectedly dark, almost apocalyptic in its presentation; I didn't expect that in a children's show, even with all we've seen before. (Well, I suppose that again, you really gotta give kids some credit: they can deal with more than you might think.) Twilight clutching Owloysius when barely making it out of the burning ruins was a great little touch: you'd really have to have worried about the little guy otherwise.
The battle with Tirek was awe-inspiringly powerful (though I was a little surprised a manavore like Tirek couldn't just eat Twilight's magical attacks); and both that battle, and the sheer amount that Tirek grew after consuming the alicorn princesses' magic drove home just how powerful they really are. (And so, for that matter, did all the random bursts of magic energy that Twilight found herself facing; it's not an exaggeration to say that she was on the brink of bursting from all magical energy she had to contain inside her.) Not that it's surprising, given how much it must take to raise the sun and the moon and all that, but wow, you really don't want to get on those ponies' bad side. Speaking of magic, it was also nice to see it acknowledged that all types of ponies have an inherent magic: it enables pegasi to fly, and gives earth ponies their strength. There's many different kinds of magic in Equestria: unicorn, pegasus and earth pony magic, but also alicorn magic, zebra magic (Zecora's potions, perhaps the same as the Everfree's wild magic), the magic of friendship (literal magic, and a force to be reckoned with!), and maybe more.
And it was interesting how the episode explicitely acknowledged that ponies are in control of their environment (weather-shaping being the most obvious example), and how they'd be lost without this. It also explains just what it so frightening to them about the Everfree, which, as its name says, is ever free, untamed and uncontrolled: to a pony used to living in a carefully-controlled environment, that's got to be terrifying. (Though the Mane Six, at this point, don't seem to have any qualms anymore about venturing into it at every opportunity.)
Speaking of the destroyed library again — Twilight's new castle is rather impressive as well, and I'm sure it'll have a library that'll more than make up for the one that Tirek destroyed. (Twily will see to that!) I wonder how long it's gonna take Ponyvillians to get used to the castle suddenly having appeared, but between how well-liked Twilight is and her having saved Equestria again, I'm sure it'll be a source of pride for the town. (Still gotta take some getting used to, though.) Relatedly: how nice that all the Mane Six got thrones there (what's the Princess of Friendship without her friends, indeed?), AND Spike. So many fan artists forget about him; I'm glad the show's creators did not. (Also: Knights of the Round Stable. Blame kittymink!)
And there was a Rainbow Power tie-in — so that's what that whole thing was meant for! I suppose Hasbro needs to be able to sell more plastic ponies; OTOH I'm not entirely sold on the designs yet, and I'm glad that the Mane Six were explicitely shown to transform back in the episode.
And here's something else I'm glad for: that despite the title and some past rumors of upcoming abdications, Twilight did not succeed Celestia and Luna (and Cadance). She's taken her rightful place as a princess of Equestria, and she's
Another random observation: the alicorn princesses looked very old bereft of magic. It makes you wonder, what role does their innate magic play in their (nigh?) immortality? If it's responsible for that, we can count ourselves lucky that their age did not catch up with them when they gave their magic away (interesting that that's even possible, BTW). (And if you'll allow me to get side-tracked just a little bit: it also makes you wonder again about the origins of Celestia and Luna. We know they were alicorns when they defeated Discord for the first time, but were they born that way, or perhaps created that way, or did they become alicorns in the same manner as Twilight? If the former (and in particular, if they were not "born" in the usual sense of the term), what is their origin? If the latter, how did they become alicorns? For that matter, I also wonder whether the first defeat of Discord came before or after the historical events referenced in Hearth's Warming Eve. But I'll stop disgressing now.)
Rarity used "Sweet Celestia!" as an uttered oath near the end of the episode: I don't recall if that's been done before, but this definitely makes it an official thing that ponies really do say now. :) (And it provides some minor evidence in favor of the royal sisters being or at least being regarded as goddesses, though given how touchy a subject religion is, especially in the USA with its evangelicals, I don't think the show is ever going to explicitely address this.)
And there were many background ponies, too many to list again: I'll just mention Photo Finish and Apple Fritter, and how Lyra and Bon Bon were seen together again. Oh, and Derpy, of course! That cute, silly, golden-maned gray pegasus mare that we all love so much.
Random notes: Pinkie throwing Boneless at the box, with Twilight going "I don't think that's going to work", and it then turning out to be precisely the thing that does work... that was hilarious. So was seeing Discord in that stained glass window that he created of himself and Tirek: whereas the latter was holding a sword, Discord had a baguette. Twilight's flying and trail-leaving while she contained all the alicorn magic was epic. (And BTW, that magic also did a lot to protect her: those blows she received from Tirek in their battle would've been bone-shattering to anypony else.)
Finally: how ironic for Tirek that his ultimate demise (well, reimprisonment) was due to the very trinket that he gave away thinking it worthless.
And about the only thing I really disliked: what looked like spoilery ads (which I avoided, fortunately) for the second part during the credits for the first part. Come on, Hub! You can do better than that.
Elsewhere: discussion in broniesaremagic. Episode follow-up on EqD.