Dennou Coil is a 2007 anime by Madhouse, cryptically subtitled COIL A CIRCLE OF CHILDREN, which indeed follows a circle of children (and some adults) involved with mysteries related to cyberspace-viewing glasses and the strange beings reflected in them. Along the way it manages to explore themes of compassion, coming of age, and the nature of reality. The show's also known as Cyber Coil, which makes sense because attaching den- (electric- or cyber-) to the front of anything and everything is kind of a running theme.
As a quick aside, I had been kind of thinking about watching this show for a while, but receiving it as a recommendation Reverse Thieves' Anime Blog Secret Santa project was the impetus that forced me to get around to it. I also intend to watch and maybe review the two other recommendations I received, the Ghibli-sans-Miyazaki1 movie Only Yesterday and Yoshitoshi ABe's classic Haibane Renmei — but not before Christmas. As it is, with this season of anime being particularly above average in the number of enjoyable shows, and DJ Max Technika 2 also releasing around Thanksgiving and subsequently commanding a shameful amount of my time, I ended up putting off the show until the last few days and watching 23 of the 26 episodes in a whirlwind of 2 days.
Art and Animation: While produced by Madhouse, it aired on NHK, and Dennou Coil's simple, cartoonish character designs and animation style bear more resemblance to other shows on that network than to the typical entry in Madhouse's portfolio. Personally, I found the designs neither a credit nor a demerit to the show; they're functional and they animate nicely, but they're hardly the kind of thing I would hang around my room so I could look at all day. The backgrounds are not really picturesque, but you can't accuse them of being lazy, and they blend quite well with the animation. The show's use of computer-generated 3D graphics is remarkably tasteful, although it gets off easy because many of the parts that are CG are cyberspace phenomena that are meant to look like CG anyway. The show has a very strong and distinctive color pallete, skewing heavily towards grays and earth-tones, with a very "faded" look to them, which is a pretty good fit for the tone of the show. In general, the animation is well-done and functional but not remarkable.
Plot and Characters: Dennou Coil is conceived, written, and directed by Iso Mitsuo, who (judging by his ANN profile) is primarily an animator, with a tiny number of script-writing credits to his name before the show. With that in mind, it's a very impressive feat; Dennou Coil's concept is inventive, fun, and thought-provoking. As a 26-episode mystery/thriller series, it shows an impressive amount of planning and depth that unravels slowly over the series' length. It's a little slow at first, and there are some filler episodes that didn't suit my taste at all, but it picks up about halfway through and manages to avoid the abrupt rush-towards-a-finale ending to which so many series fall victim. (A bit of advice: don't skip episode 14, even though its first half makes it seem like it's going to be all recap clipshow; it actually marks a crucial turning point.) That's not to say there aren't some holes in the plot and questions that don't get satisfying answers (Like, why do metabugs only appear in Daikoku City, when access to old space also exists in Kanasawa?) but compared to your average anime, it does a much better job. The characters are realistic, too realistic sometimes, prone to showing off the kinds of irritating flaws that make family members bitter at each other. Your tolerance for these kinds of things is bound to vary. In general, all but one character come off as very ordinary people almost all the time.2
Music and Sound: I can't say that there's a lot to comment on in the musical category. The OP and ED are both rather sad, but not completely melancholy songs, kind of pretty but not music I'd continue to listen to after finishing the show. (In fact, contrary to my usual M.O., I started skipping OP/ED sequences about halfway through my marathon, but that's more a reflection of the time crunch than the quality of the OP and ED.) The background music plays it pretty safe, with traditional orchestral composition for key moments, albeit clearly not performed by a live symphony; the action music is somewhat lacking in tension sometimes (especially one that makes heavy use of a generic electronic clap sample). Some of the other tracks are occasionally pleasant and moving, but as a whole, the music makes quite an effort never to stand out. The voices don't stand out much either, except for Isako's (she's voiced by the lovely and well-established Kuwashima Houko). That's not to say the voice acting is bad (it's not) or that the other voices are all nobodies (they're not), but if you're one of those seiyuu-freaks who watches terrible shows because they have an all-star voice cast, there's very little for you here.
Audience Considerations: Dennou Coil is a show that puts no small weight on family, and as such, it's fairly family friendly. There's some occasional harmless nudity in a very Japanese-family context, but it's not sexualized or emphasized or anything. I did notice there were a couple scenes where a certain 17-year-old aunt and her tight-fitting motorcycle outfit were played for fanservice, but those were such an exception to the rule that it felt awkwardly out of place. More generally, the show is based heavily in Japanese culture, with social instutions, symbols, and technology whose significance could be completely lost on you if you haven't any prior introduction to the ways of Japan. If you don't, though, watching Dennou Coil might not be a bad way to start; I don't think it will detract from the core values of the show, but there will certainly be things that seem peculiar yet would be utterly familiar to a Japanese viewer.
Overall: Dennou Coil is a series of many objective qualities and a somewhat literary bent. It has a strong story and unique setting, that got me thinking about everything in terms of virtual- or augmented-reality versus the physical. On the other hand, it's far from perfect or life-changing, and it seemed to lack a certain magic that makes a show resonate with me personally. That last bit is certainly something that differs individually, and there are many series out there with less potential appeal than Dennou Coil. It's a good watch, I'm glad that I had reason to get around to it, and I'll probably participate in Anime Blog Secret Santa again if it happens again next year. Maybe next time I won't procrastinate until the last minute to start watching in earnest.
P.S. Happy Holidays to everyone, whatever ones you celebrate.