I liked the fact it featured it wasn't a "big" story, like Trixie's return or the Crystal Empire episodes etc.; just a little bit of slice-of-life. I also liked the fact it nonetheless contained character developments, e.g Dashie taking Scootaloo under her metaphorical wing after Scoots confessed she was looking up to Rainbow Dash and trying to impress her, and I liked the fact that the CMC were (and were allowed to be by the writers!) just foals, not miniature versions of essentially adult characters: a very, very common mistake in many other cartoons.
Nice to see Princess Luna again as well, if briefly. Was it just me, or did her voice sound a little different? She also laid it on pretty thickly, with her message being made bleedingly obvious, but then I suppose it's still a show for 6-year olds.
I actually wonder if it really was Princess Luna, too – that is, if she genuinely has the ability to appear in ponies' dreams – or whether it was just Scootaloo's subconscious that made Luna appear in the dream to tell Scootaloo what she already knew, deep down. My money's on the latter; it seems more realistic (Luna's powerful, but is she THAT powerful?), and it'd also make for the better story, and the better moral.
Rarity's mountain of baggage was pretty funny; at the same time, it was good to see that she went along with her sister despite despising camping, and that she warmly comforted Sweetiebelle when she was scared. Same with Applejack and Applebloom, of course: it's got to be very, very nice to have big sisters you can rely on like that, doubly so when you're a foal.
Was it ever made this explicit before that Scootaloo cannot fly yet? At what age do pegasi learn to fly, anyway?
Sweetiebelle's talent for singing seems to have suffered a bit since we last heard it. Well, I suppose she's making up for it with volume. :)
"It is so on" was a funny throwback to earlier episodes (Boast Busters and Look Before You Sleep). And Rarity being a nag ("are we there yet"?") — I'd expect her to be a bit more mature than THAT, but then it was clearly for laughs and shouldn't be taken too seriously as far as her personality is concerned.
Rainbow Dash sleeping was cute as well.
I liked how the trees harked back to the ones in the S1 season opener episodes. ♪ Giggle at the ghostly... ♫ ^^
The headless horse is probably a reference to the Legend of Sleepy Hollow; is the "olden pony" with the rusty horseshoe a reference to anything?
Also, did anyone notice that while the episode was titled "Sleepless in Ponyville", it was actually more like "Sleepless OUTSIDE Ponyville"?