I didn't particularly like the breezies' design. They were too cute for their own good; while extreme cuteness can work, care must be taken to not let it caricature itself. Whereas ponies are simply adorable, the breezies were cloyingly saccharine; and the "tiny little elves with butterfly wings" motif is fairly worn-out as well. Even Tolkien deliberately designed his elves to go against THAT stereotype, and that was close to a century ago now.
The plot was also not the greatest ever. The breezies were overly fragile (seriously, a leaf is enough to completely throw them off-course?) and too reliant on the ponies' help, apparently unable to get anywhere at all without it; in addition, with the exception of Seabreeze, a rather refreshing character (pun intended), they were completely irresponsible and unable or perhaps unwilling to see the obvious: that despite Fluttershy's kindness, they'd have to move on, and the sooner, the better.
And yeah, Fluttershy herself: she went along with the breezies' ploy pretty much the entire time. Why? I don't think it can be attributed to her meekness alone: surely she should've seen that, as much as she was trying to be a good host, the breezies had to make it to the portal to their home before it would close in two days. If she had been aware of this and found herself in an inextricable conundrum, that'd have been fine; but for the most part, she simply ignored it entirely, and so did the writers.
The lesson was good, at least. Its delivery was not particular pointed, but it was nice to see a dual lesson with two complimenting parts: be nice, as Seabreeze learned (as they say in German, der Ton macht die Musik); and sometimes, being nice doesn't work and you have to be stern, perhaps even cross, as Fluttershy learned.
The other Mane Six only played bit parts again; Twilight also reprised her role as dea ex machina with another spell from an old tome found in the castle of the two sisters that just so happened to be perfect for overcoming the final obstacles and safely getting the breezies home. Spike, meanwhile, served as the one who inadvertantly caused the whole problem in the first place — and he was painfully upset about it, but calmed down so quickly and completely when reassured that it was not his fault that you have to wonder if this was an intentional caricature of such situations in other shows, movies or books. In the same vein, Fluttershy was very prone to tearing up in this episode — and equally quick to dry her tears again. Part of the reason why it's usually so effective is that it's used sparingly, so I hope she'll not be written to cry whenever a script calls for a dash of emotion from now on.
What else? Magic portals are a thing in Equestria. Disregarding the mirror pool and EqG (which I do not consider part of the show's core canon), have we seen any before? I felt a bit uncomfortable with this one; it raises questions about the ponies' usual modes of transportation, to wit, trains: why use those when you've got portals at your disposal? But perhaps it was a naturally-occurring one, and perhaps artificial portals, should they exist at all, are beyond the reach of all but the most powerful mages, making them useless in practice and thus failing to break the world's internal consistency and believability.
There was no song in this episode, BTW. A pity, especially since we briefly saw a mariachi (mare-iachi?) band at the beginning.
The final verdict? Sure, it was an OK episode. It had its moments; there was fun, there was cuteness. But it didn't add much to Equestria, and both the breezies and the Mane Six's transformation made me wonder if opportunities for new toy lines didn't play a role with this one as well. Still, ponies are always good, and the episode wasn't bad. All in all, I'm not complaining.
Elsewhere: discussion in broniesaremagic. EqD episode follow-up.