This spoilers contained herein are hopefuly inoffensive.
The big empty room was one of the first scenes and embodied the promise of the anime.
These two profile shots of Ritsu and Mio demonstrate the general art style (off and on backgrounds). Both the kinship and departure from Lucky Star can be seen pretty well, for a static picture anyway.
Here's a pretty picture with reflex-less hair and backgrounds. Don't recall if this is an animated scene. Again, a lot of carry-over from Lucky Star.
The scene of the lead retard Yui trying to tell the truth is about what the early story of K-ON was overall. It's not bad, set up in motion quickly, and mildly humorous, but a bit bland.
Tsumugi Kotobuki is the queen of K-ON and my personal favourite in the same way Miyuki was in terms of the earlier KyotoAni show. Both of them have too little screen time, although Tsumugi makes a curious character progress in the Special (unlike Manabi, it was set later than the main story in the continuity). Welcome, of course. BTW, although she is overflowing a cup above, it rather is an exception, inserted for the special moment. She's not generally clumsy (unlike Miyuki!), because Yui takes on that role.
Here is Tsumugi again, sharing a short "moment" with the general fan favourite, Mio. KyotoAni saw fit to pepper K-ON with moments.
Another version of the moment is a choice or a doubt. It's not directed in a heavy-handed way, fortunately.
Now what really was surprisingly common is the lump-popping violence. I honestly didn't expect so much of it.
This is apparently what passes for SD mode in K-ON. It is mercifuly rare and appropriately used. Thanks god this anime is not produced by SHAFT.
Nodoka (on the left) has an amazing voice, which is so mature that it should've felt as too old, but it hasn't. And it befits her character extremely well. If only she had a fraction more of the screen time, Tsumugi's throne would become insecure indeed.
Here we have Nodoka's opposite, Sawa-chan-sensei, teaching little brats a lesson or two. She is an explicitly spelled Christmas cake despite the gentle act she's putting up with such fidelity.
For some reason these bicycles bothered me even before the ridiculously ugly work done to retrofit Azusa into the OP. Was it hard to add her here? Why wasn't it done? I raged every time after ep.8. By the way, they adjusted the ED for the Special to add Azusa her lettered frame, which is separate by timing from the four main ones. It's like everything they did to fix it came out pear shaped. The story of K-ON's ED is a hilarious screw-up and a window into the series production process. They really do make it up as they go along!
The practice question almost summarizes the Azusa's story in K-ON. In a rational departure from the longer Lucky Star, the mid-series influx of characters was sharply curtailed. It was a correct decision.
I feel like saying something about the rather ham-fisted attempt to stroke conflict in ep.11. Surprisingly it wasn't Azusa's doing, and you know what? It would've been much better if it was.
BTW, notice the color of ties that indicates the school year. I did not pay attention to it, so I don't know what the 3rd year has.
Lots of music fans complained about how quickly Yui learned to play guitar. What's more, she continued to do the same when she provided a way stiffer challenge to Azusa than she was set up for. I wasn't that bothered by it; for stickers they had pretty big time gaps, which can be debated. And then Ui threw a spanner into the works.
UPDATE: Sagematt points to Nodoka's image song at Youtube.