It's an interesting, uncharacteristic work from Jun Maeda (writer, composer) with director Seiji Kishi and character designer Na-Ga. The animation studio is P.A.Works, but Maeda and Na-Ga are also known for their associations with famous KyoAni/Key adaptations (Air, Kanon, Clannad) and this is another Key franchise. Those three were all slow, sensitive magical realist stories ostensibly set in the real world and based on relationship-orientated visual novels.
This, on the other hand, is set in an afterlife that's a lot like a computer game. It's a high school where everyone is dead. They all died young and have regrets (or worse) that mean they can't move on. The people you need to know about are:
(a) the Afterlife Battlefront, an organisation of rebellious students who see moving on as obliteration. Maybe they're right? If you come to terms with your past life, you disappear and are never seen again. Their objective: defeat God.
(b) the angel with whom they're fighting to the death
(c) soulless teachers and students, who are basically walking, talking furniture. They're not really people.
I said that the Afterlife Battlefront are fighting Angel to the death, but since everyone's dead already, this doesn't actually mean much. Nobody dies permanently. Instead you respawn. You're dead for a little bit, then you're up and fighting again.
This makes for an odd combination of emotional weight, comedy and action. There are lots of guns. They get fired a lot. There are also bladed weapons, martial arts, explosives, etc. There are Key fans who dislike this show simply for being action-based.
Nonetheless, though, none of it's permanent and the show's actually a comedy. It's just that you don't realise at first. It's a bunch of other things too, which are stopping it from looking like a comedy at all. It takes the situation seriously. The premise, setting and gunfights are all completely non-comedic, so it took me three or four episodes to process the idea that the show was also going for laughs. What put the issue beyond doubt was ep.4 and its psychotic idea of a baseball game. They're all idiots. That's not my criticism, by the way, but theirs. They admit it, which has an unexpected kind of charm. When discussing battle tactics: "our weakness is that we're morons." The show's full of loons, which even includes Angel in her own way. We have a rich range of unintelligence, from "smarter than most of them" (Otonashi) to "magnificently insane" (Noda). There are plenty of death jokes, which hardly even counts as black comedy since these goofballs will be fine even if they, say, accidentally hang themselves. (As you do.) The show also has a nifty line in deadpan non-reaction shots and some all-out comedy episodes.
The OVAs in particular are all-out comedy filler episodes. My favourite is the 2010 one, between ep.4 and ep.5. The 2015 one's okay, but not as brilliant. (That's set between ep.2 and ep.3, incidentally.) Alas, it was also released too recently to be on my English-language DVDs.
Then you have the emotion. You'd expect it from Key and Jun Maeda, but that doesn't mean it's not hugely important.
For some people, this anime is annihilating. If you can feel the pain of all the tragic backstories, you might end up an emotional wreck. You'll see comments like "the most depressing anime I've ever seen", albeit somehow meant in a good way. I didn't get that, though. I don't think one necessarily connects in the same way to a fictional character's past life. Bad things happened. That's horrible. Wouldn't wish that on anyone. Doesn't change what we're seeing now, though. They've since died and been reborn as an unkillable computer game hero in an afterlife where absolutely everyone has that kind of backstory and half the time it's being played for laughs. If you want a tragic story to hit an audience emotionally, I think it helps to have some kind of link to the here and now.
Did I cry? Not at that stage. However the story's getting ready to sucker-punch you. Ep.9 is doing the darkness properly. We discover those links. It gets strong... and then ep.13 comes out of nowhere and trumps everything. It destroyed me. It's unique, beautiful and special. Is there any other anime that does this? Any other story in any medium, in fact? Probably not. It's an unusual premise.
There's also horror lying in wait for you if you think about it afterwards. Angel, for instance. Her physique, her lack of social skills and the fact that she's here in the first place are an uncomfortable but perfect fit with what we end up learning about her. You might also want to think about the fact that she's so accustomed to injury that she barely even flinches in ep.1 when shot in the stomach.
There are a lot of plot developments. They could have supported 26 episodes, which makes sense since the show had been planned to run that length, but the studio cut it back. Thus a lot of supporting characters never get much depth and we never hear most of their backstories. (A fan favourite character is apparently TK, to my amazement, even though he's a paper-thin character played by someone who's not acting. His dialogue is almost all in English and they cast a native speaker in the role. That's good, as far as it goes, but the character's basically talking in non-sequiturs and I was soon tuning him out.)
Anyway, I'm agnostic about the episode count. On the one hand, I'd love to get twice as much Angel Beats. I know I'd have enjoyed seeing Maeda flesh out the supporting cast and explore everyone's stories. However at the same time the broadcast version works like gangbusters and its pace gives it momentum. I certainly never thought it felt crunched or compressed. For what it's worth, these days this is one of Key's most popular properties. I'd love to see a 26-episode version, but I wouldn't say the studio got their decision wrong either. Where they messed up was with the visual novel, i.e. computer game. It was meant to be released while the anime was on TV, but it was so complicated that it went into development hell and was delayed for five years. It had 19 character routes that could combine in any order and completely change the game when you restarted.
I also like its dissection of computer game qualities, made meta in real life by it actually also being a game. As well as respawning, our heroes can hack reality if they get hold of a computer terminal. The world has bugs. One's aware that this might not actually be an afterlife, but instead a Tron-like virtual world where game characters have discovered sentience. Or even both? You could go mad imagining the possibilities.
I think what I admire most about this is the tone. It's so many different things. It's a genre-defying existentialist head trip through religion and computer games, with an army of the dead fighting to defeat God in a story where one of their allies will actually claim to be Him, not to mention the Angel and the nerd who demands that everyone call him Christ. (He's always ignored.) Is this SF? Fantasy? Magical realism fable? Whatever it is, the concepts are fascinating. However it's also a uniquely warped comedy. ("Fish hook in mouth" jokes!) It's an action story, with schoolchildren killing each other with bullets and bombs. It's a delicate exploration of the human heart. It's funny, exciting and heartbreaking. And above all, it's all of these things at once, side-by-side, deftly and beautifully.
Next time, I'll rewatch with the OVAs between the appropriate episodes and see how that changes things. Maybe they'll even make more? The 2015 one does end with a sneaky "To Be Continued..."