It's a light-hearted comedy isekai, starring a goddess (Ristarte) who's full of herself and a hero (Seiya) who's insanely rude, unchivalrous, limelight-hogging and anti-heroic. I loved it. It made me laugh a lot. Horrible slapstick things keep happening to the gloriously rubber-faced Ristarte, usually because Seiya's being appalling (again).
However it also has revelations towards the end. These were mostly what I'd been expecting... until they found one last twist into something I hadn't seen coming at all. With hindsight, everything fits together so well that it's brilliant. Powers, dates and even names all line up. That was an emotional shock.
...up to a point. In practice, the tonal mismatch is too big. The first ten episodes had been too ridiculous and Looney Tunes for us to buy any real tragedy with these characters. It still sort of worked. I liked it. I did care, up to a point, and I'd be interested in seeing how the show feels on a rewatch. (Very different, I'd imagine.) However I'd call the finale a partial success, at best.
That said, though, I still enjoyed the show thoroughly. Seiya's the kind of RPG player who'll spent a week doing press-ups in his room before fighting even the lowest-level monster. He probably spends more time training in the Divine Realm than he does actually adventuring. (He also tends to break his trainers. Cerceus the Divine Blade turns into a trauma-raddled pacifist who won't even look at a sword and just wants to bake cakes. Adenela the Goddess of War turns into a rage-filled psycho yandere.)
Seiya's also so rude that you can't translate it into English. Japanese is a very polite language, with different levels of politeness built into even the grammar and verb endings. Deliberately ignoring all that gives you ways of being rude that don't exist in English. That's Seiya.
However he's not the show's funniest character. That's Restarte, the long, long, long-suffering goddess who's been charged with Seiya and the world he's meant to be saving. Restarte might look beautiful and ladylike, but in fact she's a magnet for comedy mishaps, often self-inflicted. She's as shallow as a puddle on a hot day. She drools openly over Seiya. She'll growl, snarl, gape and pull faces so extreme that one shot turns her into a Picasso. She's the nearest you'll see to an anime version of Tom and Jerry and her voice actress (Aki Toyosaki) is living up to this gloriously.
There's a lot of buxom, but this isn't a fanservice show. If Restarte has a wardrobe malfunction, it'll be a gag. Also, in fairness, Seiya is also a source of fanservice if you like shirtlessness and muscles.
The show's also capable of playing nastier than you'd think. There's an on-screen decapitation.
This is an extremely funny show. It's also (at the end) a less successful but also interesting show that's aiming for more emotional depth than I'd expected. It's not really going for genre deconstruction, but instead is a character-based goofball comedy that's talking more about gaming character types than fictional ones. I probably will rewatch it one day, just to see how different it feels if you know about the revelations.
Apparently Seiya and Ristarte appear in the comedy team-up anime, Isekai Quartet Season 2. I approve.