It's interesting getting more glimpses into how the Mane Six tick. We all know Rarity's a bit of a histrionic at times, and that she can get fairly obsessed (which no doubt helps with those red-eye orders); apparently she's still dreaming about meeting her prince, too, despite the whole Blueblood debacle. I have to say she came across as surprisingly immature in this episode, all things considered (and I think Twilight would've agreed with that assessment), but at least she learned an important lesson: stay true to yourself, and don't try to change who you are for the sake of others. It won't work, and you'll only end up unhappy. Even if you're embarassingly cute trying to imitate a Southern drawl.
Rarity's also quite unperceptive and/or callous at times, isn't she? Moaning to Spike about how it feels to be "totally obsessed with a pony only to find out they're obsessed with somepony else" was quite cruel. (OTOH, it was also the kind of continuity I like.) I also note that she's (still?) not above using Spike's crush to her advantage to get him to help her out.
Applejack, on the other hand, was surprisingly (?) sane and level-headed. Given the stubbornness and bluntness she's displayed at times, she really handled the whole thing well, despite being caught between a rock and a hard place, in the form of Trenderhoof's unwanted attention and Rarity's burst of paranoia.
Trenderhoof, meanwhile — well, he learned a lesson, too, perhaps several. All in all, he wasn't the most likeable character, though (the way he dropped Rarity in order to go after Applejack brought up painful memories of Blueblood; 'm sure Rarity felt the same way), and he's further evidence that many stallions featured on the show are exaggerated, stereotyped or clichéd in some way. (There's exceptions, of course; Soarin' comes to mind immediately, for instance.)
And there were cameos, of course. Vinyl made an appearance, Amethyst Star, Lyra, Dinky, and many others; Derpy again as well, with another obvious nod to bronies and the controversy surrounding her appearance (or, rather, subsequent Bowdlerization) in The Last Roundup when Trenderhoof points to her as an example of "the unappreciated". And Lightning Dust was there! And in her Wonderbolts trainee uniform, no less; I sure hope that means she didn't get summarily thrown out.
What else? No song (just a limerick), but many "best faces" that I'm sure EqD will have a field day with. Applejack's "fashionista" pictures were quite good — she could probably land a modelling gig if she wanted to, and I'm sure her pictures would end up pinned up in more than a few lockers. Rarity's designs continue to impress as well, and her farm garb was quite cute as well (the first incarnation, anyway; not the coveralls and straw hat she was wearing later on). Also: ponies apparently pull their own plows. Makes sense to me!
Elsewhere: discussion in broniesaremagic; episode follow-up on EqD.