It's okay. It's a spin-off of Is It Wrong to Try to Pick Up Girls in a Dungeon?, set at the same time as the main series but following a different set of characters. Sometimes they overlap. I found it a bit lumpy and inconsistent in what it's doing, but still basically enjoyable. It improves in the second half, if that helps.
It's set in a sword-and-sorcery fantasy RPG universe where the heroes are adventurers. Almost everyone's Level 1, with not many ever reaching Level 2. The strongest adventurer in the world is only Level 6 or 7. The only bit that's not ripped straight from AD&D is the god sponsorship system, in which the adventuring guilds are called familias and are run by actual, literal gods. They've come to Earth (or whatever this world is called) and they do all the things you'd expect of their mythological namesakes, such as squabbling, sexually harrassing their followers, etc. It's a fairly light-hearted franchise, but serious about dangerous monsters and threat levels. The original show's protagonist is Bell Cranel, a nobody who worked his way up to AWESOME!!! while being unaware throughout of the increasing number of buxom hot girls who were taking a romantic interest in him. Yeah, that's right. It's one of those shows. That said, though, it's also playing its dungeon-bashing storyline straight and it's an enjoyable romp that made quite a splash in 2015. It's fun and exciting, with a likeable cast.
This spin-off, though, is about Aiz and her comrades in Loki's familia. This puts it at a disadvantage. Firstly, the cast aren't as likeable as Bell and Hestia. Aiz is an apparently emotionless stoic and the show never really gets inside her head, although apparently the original light novels do better. Meanwhile her colleagues are only okay. Bete is a loud-mouthed dick, Lefiiya has a clingy crush on Aiz, Loki is a serial molester, Tione and Tiona are likeable but fairly flat characters and everyone else is basically there to be badass. I liked Finn, for instance, but he's hardly a dramatic focus. It's a two-protagonist show, really. Aiz is the opaque focus and action hero who actually does stuff, while Lefiiya is the one with visible desires and a character arc. This basically boils down to her getting stronger and overcoming her jealousy of Bell, though, which in the end even seems to be mysteriously true of the party as a whole.
The other problem of being focused on Loki's familia is that they're so freaking strong. Lefiiya's the weakest of them and she's Level 3. Aiz is like the Terminator with underboobs and she's not even the party's strongest fighter, since it contains no fewer than three Level 6 adventurers: Gareth, Finn and Riveria. Of course there's nothing wrong with strong heroes per se, but it leaves less room for development (although not none) and it means that there aren't many people or monsters in existence who can threaten them.
The show has three phases, I think. The entire first half is fairly plot-light and not really that interesting, feeling more like a parasite on the parent series than a proper story in its own right. A nicer way of putting it might be sword-and-sorcery slice-of-life. The thing I noticed most about it was the salacious content, with undressing, groping, boob size discussions, women being lascivious, etc. These episodes were okay, but dramatically they're treading water.
After that, the second half grows a plot. A new character gets emotionally meaningful content in ep.8! (Everyone calls her the Banshee and she's thought to be cursed, including by herself.) Ep.7 is genuinely quite interesting. The story gets good, someone appears who can threaten Aiz and I found myself actually wanting to watch episodes.
After is the two-part finale, in which all hell lets loose for ep.11 and ep.12. They've gone looking for trouble, yes, but boy do they find it. Those were some serious action sequences. It's impressive and pretty damn cool... until it all ends in an "is that it?" They've beaten the monster. End credits. Eh? It's just a monster! What about the villains? The show plays some degree of catch-up there in post-credits scenes, but even so I wouldn't call this a finale. It's just set-up for Season 2. Now we just have to see if one ever happens.
Would I call this a good show? Um... eventually, with caveats. When it's good, it's good. When it's not, it's still watchable (if occasionally a bit eye-rolling). Have I deleted the episodes? No, but that's partly because I might do an experimental interleaved rewatch of this and the parent show one day. I'm curious to see how that would go. Besides, this season will probably improve in hindsight if a Season 2 does come along. I don't mind it.