Great episode! I enjoyed this a lot. Hooray for world-building! I didn't care much for Dragon Quest (Crackle aside), but this was a massive improvement and is much closer to what I hoped Dragon Quest would be. It was also a great follow-up to DQ, with lots of call-backs, and fixes the problem of Spike apparently completely turning his back on all dragons forever at the end of that episode.
Also, pretty obvious, but this felt very very How to Train Your Dragon inspired, down to the gigantic dragon leader that commands a massive collection smaller dragons and has the power to summon them to his location.
Ember is a really cool new character, and I like her design a lot! However, the whole "Let's be friends! Friendship is awesome!" vs. "'Friendship'? I do not understand this concept and have no need of it" back-and-forth was a bit simplistic and perhaps too similar to the Griffons. We have yet another species/culture that doesn't understand the concept of "friendship"... Which is odd in both cases. Gilda naturally befriended RD as a kid, and Gustav didn't seem particularly unfriendly. Garble's group sure look like "friends", and the (ex-)Dragon Lord obviously cares about Ember.
But ehh, kid show about friendship. It works well enough for target audience I suppose, and gets the message across. And I enjoyed Ember and Spike working together a lot, and her gradually understanding and growing to accept his friendship ("WHAT IS THIS" "it's a hug") was pretty cute.
I enjoyed the stuff with Garble this episode too, which I don't remember doing in Dragon Quest, and thought they handled his dynamic with Spike really well.
Lots of cool animation and set-pieces too with the trials this episode too. A nice change of pace, and I love dragons so I loved this stuff.

Ember's dragon-armor was rad as well (if possibly redundant

).
Of course, I loved Twilight nerding out over studying dragon culture. Just Twi being Twi. Good stuff.

And I like that Ember is going to be exchanging notes with her about dragon culture. I'm sure she'll return at some point, and I look forward to it.
Twilight and Rarity sneaking around in their environmental camoflage to keep an eye on Spike was amusing. I'm glad they came up with a nice twist on the Crackle joke rather than just recycling it. Having them waiting in the wings in case of an emergency helps it make sense that they would allow Spike to participate in a dangerous competition (Ember almost drowned, after all), but they're still letting Spike handle things himself for the most part.
Backtracking to the start, it feels like it's been a while since we've seen Rarity mine gems, so that was nice to see again. And seeing Twilight, Celestia, and Luna just hanging out at Twilight's was great but I wish we saw more of them chatting about... whatever, before Spike bursted in. I know that's the joke, but I would loooove to just see those three hanging out in a slice-of-life situation. More casual Celestia and Luna please! (Preferably with Luna injected with personality again a la Luna Eclipsed and Cook's comics, please)
The episode was super-predictable from the moment Ember was introduced (obviously Spike would help her become the Dragon Lord), but that didn't bother me at all because I was enjoying everything that was going on so much. Overall, great stuff.
