I'll start this review by saying I started watching this show with no prior knowledge about the writers and the premise, so I had no idea what to expect. What I found was a mature and compelling story that kept me entertained throughout the season.
Even in such an amazing season, it managed to shine through as the anime that defined the summer of 2014. Even compared against such great shows as Gekkan shoujo, Tokyo Ghoul, RE:Hamatora and Aldnoah;Zero, Zankyou no Terror stood on top.
There are many stories that focus on anti-heroes and terrorism, yet none have come close to the level of maturity found in ZnT. This shows succeeded in areas that other shows such as Death Note faltered. You will find no edgy character development here; no shonen-esque elements. This is the kind of show that you could quite happily show to any non-anime orientated friends with confidence that they won't leave mid-way through, or that you will have to justify why so-and-so is making unnecessary fanservice.
The art style of ZnT perfectly fits the tone of the show. There are many still-life scenes in ZnT, and each one perfectly captures the essence of Tokyo. After seeing Tokyo rendered in both Tokyo Ghoul and Tokyo ESP, the realistic calming images in ZnT were a breath of fresh air.
The character design also mirrors the art style: realistic enough to provide a sense of severity, yet different enough to give the show an underlying artistic element.
Despite some background characters lacking detail in some parts, this is expected for the first release of an airing show and does no detract from the overall excellence.
There are very few shows in which I decide to buy the OST, and even fewer in which I will continue to listen to the songs many weeks later. These songs bear a strong resemblance to 'songs from a cold country' which is a phrase that will become clear if you watch ZnT. In short: the sound is beautiful, elegant and very melancholic.
Both 9 and 12 have starkly contrasting personalities: 9 being blunt and mature with 12 being childish and playful. Lisa describers them as having'a smile like the sun and eyes like ice'. However it goes far deeper than that. Underneath 9's calm exterior lies indescribable grief, and under 12's smile lies a form of severity to match 12s.
At this point many watchers would criticise Lisa fir being 'bland' or simply a plot device. However it is impossible to imagine the show without her. Not only does she create a contrast, with her troubles with her mother against 9 and 12 orphan statues, she shows a great deal of development over the show's progression.
Finally I will touch on the characters in the police force, and how ZnT manages to capture adults in such an appropriate way. The police are neither shown as mindless soldiers, nor as clumsy un-organised oafs, and although the duo play along with them, the police are never antagonised.
From episode 1 I was hooked. No other show kept my interest like ZnT. Now that it is over I feel as if I have gained something from the experience
To summarise, Zankyou no Terror showed a level of maturity and elegance I never expected from anime, and it is my hope that other shows in the future will learn from ZnT.