I liked Pinkie in particular in this episode; she was very much in line with how she was originally conceived, avoiding the over-the-top zaniness that later plagued her. Dash, OTOH, was a bit OOC — since when is she outright keen on meeting monsters? From an in-universe perspective they are an existential threat, so realistically she should be more concerned.
I was surprised that Twilight Sparkle could be overpowered so easily, but perhaps she was caught off-guard. And given how Starlight Glimmer's name mirrors Twilight's, I imagine that she's intended as a relatively major villain who we've not seen the last of and who is presumably fairly skilled with magic. (Still, Twilight is the very Element of Magic.)
Starlight Glimmer also looked a bit like Suri Polomare, didn't she? Must be a color scheme that's common for antagonists, somehow. :) (I think they also reused some of Twilight's facial expressions for her.) Night Glider, meanwhile, reminded me of Silverlay, and there was another pony that looked rather like Limestone (Blinkie) Pie.
And then there was Double Diamond, whose color scheme (white mane/tail/coat, blue eyes) was clearly a rip-off of mine. :P Even his special talent (assuming it was indeed skiing) was snow-related — could it be any more obvious? :P
The loudspeaker was a bit weird – does Equestria have electricity now, or was it powered by magic? The balloon binoculars were amusing, though, as was the balloon bridge.
All in all? Decent start for the season.
Elsewhere: discussion in broniesaremagic. Episode followup on EqD. Review by drhoz.