Okay, so, now that it's here, a few things I particularly enjoyed:
The rings, obviously, are great.
Natsuki is so cool looking. I love that she and Yuu play the bean-bag toss together.
Akari drinking out of Doujima's soda and Natsuki and Koyomi teasing them is great.
The hand-holding back at the back of the gym, shades of the Stuco election photo.
Flashback montage: If they make a second season of the anime, this is going to break me. I got teary as it is.
The cafe has employees now!
The return to the stream is also a nice last stop for the series.