I really enjoyed it. It's lampooning the "hero transported to a fantasy world" genre, with "heroes" who are absolutely terrible at heroic deeds and hardly ever seem to go on adventures anyway. Their main impetus for doing so tends to be when Aqua's racked up an even worse debt than usual.
Oh, and it's also funny.
The protagonist is Kazuma, a sixteen-year-old boy who's played lots of computer games. In this new world, though, he's an adventurer who can learn any skill, including magic! He also builds a party of powerful female adventurers:
1. AQUA, a goddess. No kidding. She's a proper goddess. She also has related priest abilities like turning the undead.
2. MEGUMIN, a magic-user with what might be the most powerful offensive spell: Explosion.
3. DARKNESS, a knight ("Crusader") with great physical strength, unshakeable honour and loyalty and no fear.
Sounds good, right?
Well... Aqua's an idiot who seems to specialise in party tricks and racking up enormous debts. She can occasionally be dangerous, but mostly to her allies or to perfectly nice people that Kazuma's trying to talk to. Most of the party's problems tend to be her fault. Meanwhile Megumin's magic spell is powerful, yes, but it's the only one she knows and she refuses to learn any others. She loves Explosion. She doesn't want to cast anything but Explosion. She doesn't care that it's worse than useless in all sorts of circumstances (e.g. underground, confined spaces) or that it requires so much magical energy that casting it incapacitates her for the rest of the day.
And then there's Darkness. She's strong, but also really bad at attacking. She's never successfully hit a target yet. This is a drawback in the party's fighter. Instead what she'll do in combat is try to be a wall, i.e. standing there and letting the bad guys attack her. She derives pleasure from this. She likes being attacked in general, in fact, and not-so-secretly hopes to be carried off for torture, abusive ill-treatment and humiliating sex slavery.
It's hardly surprising that Kazuma's become sarcastic and cynical, although admittedly he'd already been lazy, rude and perverted. He's also happy to be unheroic if that's what it takes to win a fight (which doesn't happen very often). It's also worth pointing out that he's annihilating all the cliches of the standard light novel protagonist, which makes him refreshing and different in a way that doesn't mean "unlikeable" (which has become the other harem hero cliche).
There's more to say about that perversion, by the way. It sounds as if this might have been toned down from the original light novels, about which some readers say that Kazuma sexually harasses his female companions. (I won't be reading them.) If so, though, I'm happy to say that he doesn't here. It's not that kind of show. That would have been unpleasant. Sexual elements are only raised here when it's a plot point. That would be ep.3's panty-stealing (unintended and a minor element) and ep.9's succubus dream house (outrageous sex comedy and a standout episode in its petrifying way). Apart from that, though, there's nothing. Kazuma's a virgin from start to finish and I was actually a bit surprised when he started perving in ep.9. The show's main outlet for sexualisation is mostly just some mild-ish fanservice, in fact, which usually means either an Adventurers' Guild receptionist with cleavage, or else Aqua's favourite combo of a frilly micro-dress and no knickers.
(UPDATE: no, I take it back. I've just watched the OVA. He's even worse than I'd thought.)
Personally, I had a ball with this show. It works for me because I found the characters likeable and I appreciated the way they end up sticking together even when they're being lunatics, lazy, staggeringly useless or driven by inappropriate motivations. Beware, though. Not everyone agrees with me. Kazuma and Aqua can be pretty terrible, especially to each other, but I don't mind that since it balances out and everyone tends to get as much stick as they deserve. It's not a nasty show. I found it warm. The bad behaviour is about poking fun at the genre, not about genuine nastiness or anything like that... and in any case even the genre skewering is affectionate. Besides, for all Kazuma and Aqua's bickering, they're also closer to each other than anyone else here and I wouldn't be surprised if they got together in the end eventually. They're rude to each other, yes, but with the kind of give-and-take that only comes with familiarity.
Look at the monster bashing, for instance. There can be something a bit uncomfortable about the way that fantasy RPGs are basically about ethnic cleansing for hire, with an awful lot of the games I've played boiling down to "hunt down and murder sentient beings for money and fun". If you're dungeon-bashing, then it's not even self-defence. You're invading their homes and murdering their women and children. Here, though, so far it's all been rather nice. In the episodes so far, our heroes have killed: (a) giant toads that swallow you whole, (b) flying cabbages, (c) the undead, (d) a giant spider-robot mecha at the season finale. Very few of those have been sentient and all have been morally unobjectionable.
The only exception to that would be one of the Demon King's generals, Verdia, who subverts genre formula in a different way by having no destructive intentions at first and only marching irritably into town after Megumin did something really stupid. Yes, he's an evil undead supervillain who carries around his own severed head, but we all have our little issues. He hadn't been hurting anyone and it's all Megumin's fault. Would it be okay for our heroes to kill him? Dunno about "okay". The more important word is "difficult". He's really powerful. Also evil. However of course he's technically dead already, not to mention kind of whiny and needy.
Yup, Verdia made me laugh too.
It's fun. I want more of it. I'm also watching it alongside Re:Zero, which is the other 2016 anime that deconstructed the genre of "hikikomori teenage gamer in a fantasy RPG world". They're both quite good, apparently. That should be an interesting comparison. The only quirk is that I wondered if the anime wasn't abbreviating the source material, with the odd episode occasionally mentioning acquaintances and adventures that we'd heard nothing about. That wasn't in a bad way, though. It works. Bring on Season 2!