Overall, the episode was just okay. I'm glad we're out of the two-parter and will (hopefully) return to the
Slice of Life episodes after the break.
That said, there are two comments I have to make:
1. Discord...well, he really comes across like an idiot
Smug Snake in this one. You know, EXACTLY LIKE Q WAS. I'm not talking about the "All Good Things" Q people like to remember, I mean the "crappy first season" Q. Or the "got pimp smacked by Ben Sisko" Q. Or the "I'm so horny" Q from Voyager. For all his power, Q spent most of his appearances as a petulant manchild, tormenting the Enterprise simply because he was bored, and throwing a fit the few times he lost.
I actually thought Discord's defeat was in-character. He thought he had won. He thought the ponies were still broken after last time, or that he could just break them again.

Perhaps he even thought they wouldn't be a problem since they weren't as powerful on their own as Celestia and Luna.

In any case, his own arrogance left him wide open to taste the rainbow.
2. To all people complaining about Luna not appearing...why? What would she had contributed? Luna is mentioned in the first part, and the only way to defeat Discord is to use the Elements of Harmony, which neither Celestia or Luna can do anymore. The production team know she exists, they acknowledge she exists, and they've already said she would be back this season. Only two episodes have aired, both of which were produced
during season one, and already you're screaming because Luna didn't show?
And even if she did, what Luna would they use? Playful Luna, shy Luna, vengeful Luna, evil Luna, you name it, it's been done. Fanon has gripped the character so tightly there's no way any writer or animator can do anything with her without setting up a
Flame War of epic proportions. Personally, I'd prefer Luna have a more focused episode than getting shoved into an already overly-packed two-parter.
That said, I can't wait for the rest of the season. Hopefully we'll get some word on when the next episode will air soon.