Overview
It's the story of two twin sisters from Hokkaido who are attending highschool away from home, in Tokyo. We get to follow them around for a few weeks at school and when they go back home to visit their family.
After some of the other reviews I kind of feel I need to state it: this is not really yuri (in the Western sense). Its not even romantically explicit much, other than for the purpose of comic relief. If you prefer to read too much into it, that's your choice. The intimate undertone is definitely there and I can't honestly assume the producers didn't count on it being a major attraction.
But that's the key difference: it's about intimacy, not sex. We're being allowed to peek into the personal space and close relation of two twin sisters and there's huge amounts of value right there without having to go for anything more explicit.
Animation
Really smooth artwork, you can tell they've put a lot of work into this. There's a lot of detail, both on the characters and the backgrounds, no reusing of scenes, no cheap tricks. All the frames, even the most mundane ones, are so chock-full of interesting little details I had to frequently pause it to examine everything. The images are so rich they tell maybe half the story almost all by themselves. And I particularly enjoyed the way they draw the characters themselves: the hair, the clothing, the accessories.
This is outstanding and the only reason I didn't give it a 10 is because I didn't get to see it in HD.
Sound
The soundtrack is quite pleasant. I wouldn't call it memorable but it fits very well with the mood of the scenes and the ED tracks (yes, there is more than one! featuring various artists) are perky and nice. BTW, make sure to watch every episode to the end, past the ED track, there's usually an extra scene there! And don't miss out on the still frames during the ED, there's a message in there as well.
I appreciated the fact they took care not to overdo it and that the music is only there when it's really needed, otherwise leaving silence for us to appreciate the voice actors. The transitions from dialogue-only to music backgrounds are very smooth, making for excellent continuity. Speaking of the actors, they do a great job. The main characters have great voices, very well suited to the way they act, and they did an outstanding job on voicing them even during the younger flashbacks -- different, but distinctly recognizable.
Story
It's not fair to say there's no story. True, there isn't an overarching plot spanning across all the episodes, but there are minor substories spread across several ones. You could say that the major plot driver is in fact exactly what we're being shown: the regular lives of the main characters and their relation.
They are highschool students nearing graduation, living away from home in the big city, and this comes with lots of things that need to be taken care of. There's exams, planning out where to go to college, making better use of the very limited space in their dorm room, the commute, wondering when the new more spacious dorm will open, weight watching. Even casual, normal day-to-day life gives you a lot to do when you think about it, doesn't it?
And that's not all. There's the little things like choosing Christmas or Valentines presents, getting to eat a certain sweet, forgetting your umbrella on a rainy evening, spilling egg white on your favorite pillow. These things may be small but they come back later, lending a solid feel, making you feel there's a well-put together story after all.
Want more? You got it. We get lots of flashbacks into how things were and came to be, when they started highschool, when they were little, when they first met Saku-chan and so on. Everything adds to the main story in neat layers.
Bottom line: it may qualify for "shoujo-ai" and "yuri"... but at the same time it definitely qualifies for "slice of life" and "coming of age". This is not empty and unsubstantial, story-wise.
Characters
I think by now you've gathered, from the description of the other aspects above, that there will be a lot of detail to the characters. The main characters get the spotlight, naturally, and we get to see an extremely vivid presentation of both. Even though they are twins they are quite different, and once you get to know them better they will certainly suprise you. Yuki-chan seems ditzy and airheaded while Kana-chan looks like she's assertive and has a cool head, but in fact things are not always as they seem. Often enough, it's Kana who gets herself into all sorts of trouble while Yuki shrewdly navigates around rough spots. I don't want to give away any more so I'll leave it at that, but let me assure you, you will not be dissapointed at neither the depth nor the development of the characters.
The minor characters also deserve a few words. Saku-chan is a younger colleague who's obsessed with Kana, follows her around all the time, snaps pictures of her, collects whatever stuff of hers she can get her hands on and tries to spend time with her as much as possible. She serves as comic relief mostly but she also has decent details and depth of her own, and she also serves to further enrich the outline on the other characters. Aside from being an obsessed-fan slash stalker she has genuine feelings for Kana and it's always amusing to see the others take advantage of her obsession in all sorts of amusing ways, although it's not always clear who's taking advantage of whom. :)
Last but not least, Shi-chan is the twins' younger sister who's still attending secondary school back home in Hokkaido. There's an entire subplot right there which I will leave for you to discover, suffice to say that there's a good amount of drama stemming from the twins' departure from home and the younger sister feeling somewhat left out.
And this brings us back to the yuri overtones. Is there enough reason to read too much into it? Are Kana and Yuki a little too much "into" each other? Sure. But see, the thing about this is that it's all in your mind. If you'd prefer there to be innuendo and sexual overtones, you can play it that way. If you just want to enjoy it as a light-hearted story about everyday life, that's there too. The producers managed to create a wonderful balance and the characters are great just by being themselves.
Value
I may not watch this series again right away but I think I might definitely feel like it sometime later. There is such a ton of details to everything, soundtrack, image, characters, that I feel like I haven't taken it all in with just one run. It's amazing stuff for such a short series (7 episodes running 8-14 minutes each, plus some extras).
Would I buy the soundtrack CD/ONA DVD/series DVD? I might! I'm sorely tempted. See, they come up to around $100 together which is quite steep for me and I'm a cheapskate... but like I said, I'm soo tempted. This is wonderful stuff and I definitely want to own it, soundtrack and all.
Enjoyment
I can honestly say I've loved watching this. What I got was way more than I had any reason to expect. If I may quote what somebody else commented elsewhere: it's as sweet and fluffy as pink cotton candy. Which means a lot of fun! But I would not agree that it was insubstantial. If it leaves you feeling great it cannot be all that inconsequential.
