I've got to say, Twilight really isn't a good teacher (yet). There's nothing wrong with her learning methods, but her teaching methods leave something to be desired; at a minimum, working with a student rather than against them (as Twily was) is important. As such, it's fitting that Twilight was the one writing the friendship journal and having learned a lesson in this episode. There really are different approaches to learning, and finding one what works for YOU is the most important thing.
The various methods that the rest of the Mane Six tried varied from interesting and well-intended to silly. I liked Fluttershy's play, and if it had been a little less cryptic (and catastrophic), it may actually have helped. On the other hand, I'm still not sure what Rarity even intended to do — but hey, any excuse to sew historic costumes and put on an impromptu fashion show, right? :) Speaking of which, that short exchange between Dash and Rarity – "Rarity, you look ridiculous." — "I'm going to ignore that comment out of my desire to help you." – really made me laugh. Move over, AJ, there's a new Element of Honesty in town! (That said, I did like Rarity's costume, and I still like how ponies design clothes in such a way that their cutie marks remain unobscured.)
And Dashie's method of learning actually made sense to me. Flying is another form of bilateral stimulation, akin to walking, biking etc., and as such should indeed help the brain process information. I also liked how quite literally everypony in Ponyville ended up helping Dashie prepare for her exam in the end: and it really paid off! That "100%" mark she got should open a few doors for her.
The glimpse of Equestrian history (not just the Wonderbolts, but also an off-hand mention of the aftermath of Luna's banishment) we got was fascinating. So this means Luna actually never knew about the Wonderbolts until she returned, right? Sure makes you wonder just how many things the other ponies – and the viewers – take for granted that Luna is completely unfamiliar with.
As for the Wonderbolts themselves, their history reinforces the militaristic nature they were given in Wonderbolts Academy. I'm still not a fan of that.
Another thing I wasn't such a big fan of was Pinkie's rap. I always like songs, but like Sweetie Belle, I really prefer show tunes, and rap seemed out of place in Equestria. OTOH, Vinyl lifted her glasses for a brief moment (after previously having done so in A Canterlot Wedding Pt. 2), and reveals her eyes to be purple again. (Which suits her, BTW, although I'm still rather partial to the red eyes that were previously hypothesized for her as well.)
What else? Angel and Opal as Celestia and Luna were cute, as was Winona with a horn. I enjoyed seeing Twilight fly. Rainbow Dash's bout of silliness with Owloysius and Spike was very funny. Spike as a director for Fluttershy's play was cute, too (and I felt sorry for the poor guy there; he just can't catch a break). Dash got her shades out again, and appears to have tried to use them to hide the fact she was dozing off — maybe she should ask Homer Simpson for a pair of his. :P And Rarity's line about Dashie's "inner Wonderbolt" was very funny, too.
So yeah, all in all? Enjoyable episode.
Elsewhere: discussion in broniesaremagic. Episode follow-up on EqD.