It's the little things that can make or break an anime. I don't think it has ever been clearer than when watching Tokyo Magnitude 8.0. I got attached to this series right from the first episode, yet if you asked me to tell why, probably couldn't since I'm not quite sure myself.
Well, anyways, the good points I can define. The characters and their actions are low key and believable enough to pass for real people and, while they can get very emotional and close to losing it, never really cross the line into Stupid Hysterical, a problem that plagues a bit too many shows.
The main cast is also likable, which is a big plus seeing as a disaster flick pretty much falls flat when the viewer couldn't care less about the characters. Mirai starts out as a gloomy complainer, trying very hard to both act like a grown-up and at the same time look like she doesn't really care about doing so, the archetypal user of the line "It's a pain..." and always ready to offer a cynical counterpoint to her brother's smiles, but still very much there to look after him when it counts. This is before the titular earthquake.
After both being forced to grow up by the earthquake and its ruthless crash course in the frailty of humans and everything they've created but also helped to grow up by the kind understanding of his traveling companions and the goodness of various people they run into, we've bid farewell to the forced indifference by the end, making way to a young lady who's still somewhat gloomy but knows her limits notably better and can appreciate things in a way she never could before.
Mari, meanwhile, is a person pretty much anyone would be able to appreciate during a time of crisis, a woman who can keep level-headed when there are people needing her and help those who can't necessarily help themselves, made all the more respectable by the fact her own family's fate is unknown, too. Yet she never leaves the siblings behind to check up on her family faster because of simple human empathy. And when she can finally afford to get emotional, it's a sight worth waiting for.
Finally there's Yuuki. About all kid characters in catastrophic scenarios could take a lesson or two from this boy. He's basically the positive counterforce to Mirai's negativity, yet his smiles never really come across as dumb obliviousness but instead a child trying to keep things down to a scale he can understand and, at the bottom of it all, make his beloved big sister smile with simple displays of love and caring. After so many bratty children and the stink they cause he was a refreshing breeze whom I started caring about in the first episode more than many other characters during their entire series.
The other characters left a good, non-clichey impression, overall, but didn't get enough screentime for me to get attached to them like these three. However, this brings my attention to the next point I liked about this show: it showed the best of human nature. Shows that show the utter monstrousness and depravity humans can go to aren't exactly scarce, but the other side of the scale is fairly empty. Hence seeing all the people, both professionals and volunteers, helping strangers and conducting rescue operations, while still keeping things realistic in that not everyone they met was all smiles and helping hands, was a very welcome sight and good enough that I'm willing to ignore the fact that in real life you'd probably have looters, criminals and all kinds of assholes trying to profit from this one way or another.
Also, I think one of the best things about this show was the subtle facial expressions that were usually a better indicator of the characters' true feelings than their words. They also didn't shy away from the destruction caused by the earthquake. Objects sent flying/falling, windows breaking and ground cracking were all portrayed without skimping on the animation. Even certain large-scale objects go crashing down with the appropriate chaos and destruction.
Another strong point would be the voice acting. Mirai and Yuuki scream each other's name a good number of times throughout the show, but the distress in their voices makes it sound heartfelt instead of corny. Their mother also gets a special mention despite only appearing in two episodes. A performance good enough that even I, who don't usually notice these things much, took notice this time. Also liked the OP and ED, and while I mostly didn't notice the soundtrack otherwise, they did utilize it very finely in one scene.
Also must mention that I can count the amount of shows I've actually cried to on one hand, probably, but this one took the cake. It even got me crying out of sadness whereas most others have been tears of happiness. So... yeah. For someone like me who likes to get emotionally involved, this show was gold. 9+/10 About the only reason I don't give this something even higher is that I couldn't really pick out a stand-out scene or something similar.