It's the second in a two-film live-action adaptation of Assassination Classroom and it was the 8th highest-grossing Japanese film of 2016, at the Japanese box office. It's okay. I don't mind it. It's a perfectly good flick with some good bits, although it has a slightly scrunched first half-hour, some thematic drift (probably deliberate) and some variable acting.
We start with children trying to kill Koro-sensei. This might sound like a given. All students want to murder their teachers! No, just joking. Koro-sensei's a giant yellow octopus with superpowers and a 10,000,000,000-yen bounty on his head, because he's said he'll destroy the Earth. You'd be trying to kill him too. However this is a bit startling if you've just watched the corresponding second season of the anime, where his students realised long ago how pointless it is trying to shoot or stab a superbeing that moves at Mach 20.
Well, that's okay. These students are more gung-ho than their anime/manga equivalents. Fair enough. Different medium, different priorities.
The film's first half-hour is a slightly over-condensed retelling of some of the corresponding events in the manga. To me, it felt a bit frantic. Scenes could have used a little more time to breathe. The kiss scene doesn't work, for instance, and then is never referred to again anyway. Admittedly that's sort of to be expected, since a feature film could never cover all the material of a long-form manga or TV series, but even so I couldn't help noticing that almost none of the students get individual focus. Karma and most glaringly Nagisa are just sort of there. There's none of the "psychopath vs. nice guy" tension with the latter. He doesn't have any relationship with Kaede, although in fairness she's the one student in this film who actually does get some focus.
I found myself noticing, for instance, that the actors are obviously much older than their characters. They're in junior high school. They're meant to be fourteen or fifteen. However Maika Yamamoto is 18, Ryosuke Yamada is 22 and Masaki Suda is 23. I also wasn't always convinced by the cast. Kang Ji-young irritated me as Bitch-sensei, even before she says "showtime". (The skintight black leather and rocket launcher compensate somewhat, but that bit caused me pain.) Kazunari Ninomiya still doesn't compare with Jun Fukuyama as the voice of Koro-sensei. I'm also not sure about Ryosuke Yamada as Nagisa, even though his performance in the first film won him a Japan Academy Award for Newcomer of the Year. I think he's playing Nagisa as a girl. (No, not effeminate. I think actually being female is what he was aiming for in his performance. It's a "finding your character" actor thing.) Admittedly I think this is fine in principle and it has textual support, with manga-Nagisa often being mistaken for a girl, but what it actually does to Yamada is to make him kind of annoying.
I quite liked Maika Yamamoto, though. She brings her scenes alive.
Fortunately, though, things recover when we reach Koro-sensei's backstory. That's genuinely strong and easily the most successful part of this adaptation. I have only two quibbles. 1. I got mildly irritated with the cliched one-note blue lighting in the Reaper/Yukimura scenes, which I think would have been visually stronger with different light on Yukimura's side of the barrier. (Yes, I'm being trivial.) 2. I also regretted the lack of violence, which most glaringly means we don't see what happened to Yukimura. (Japan keeps getting stricter in what you can put on-screen.) This section is still excellent, though. The film really slows down and takes its time, giving the two actors every opportunity to talk and create their characters. We spend 25 minutes living that backstory. It's very well done indeed and it kicks the film back into gear, with everything thereafter feeling in command of itself and not rushed.
That's not to say that there aren't still flaws, though. The "kill vs. save" class battle has been boiled down to just Karma vs. Nagisa, which I don't think really makes sense. Mind you, I'm not convinced it made sense even when the manga/anime had all of them fighting, but at least there you ended up believing that the class would accept this gladiatorially determined verdict. Here, not so much.
It's basically good, though. Koro-sensei's defeat of the big baddie at the end was so abrupt that I actually rewound to see if I'd missed anything... but that's not a problem.
I do regret one fundamental change they've made, though. Maybe it was unavoidable. Maybe it had to be this way if you were compressing the story down to this format, but they've almost lost the "classroom". It's Assassination Classroom. To me, the anime's really about teaching. Koro-sensei is a teacher who's driven entirely by showing his students how to become better people. He advises them about their exams (not here). He opposes the school's demonic headmaster (not here). His response to an attempted assassination is to help his would-be killer grow as a person and do better next time. In the end, the killing is almost beside the point. The most important part of the anime is its "what happened to everyone" final episode, which is almost unrepresented here.
However this film's focus is on killing, not teaching. It has non-stop murder attempts in the first half-hour. It tells us nothing about Kunugigaoka High School's educational policies and it doesn't really let Koro-sensei do any teaching. (It doesn't really let Koro-sensei do much of anything, in fact. He doesn't get much of the limelight.) The film's telling its chosen story reasonably efficiently, but I think it's been dimished by its decision to underplay the educational side of things.
In short, it's okay. Not great, but it's part two of a perfectly watchable adaptation of one of my favourite anime/manga stories of recent years. It's weaker than its first half (as with the anime) and it's also weaker than the second half of the anime. It's fine. It was a successful film, at least financially, and I don't think you need to avoid it.