I'm writing this as somebody who has read the novels and understands the entirety of the series plot.
Visually Departures is the best the series has ever looked. There were some cool nods to LN fans with some of the characters casual clothes from SWEET! getting animated. The service scenes were never going to be on the same level as the novel, because that would have certainly pushed it into R18 territory, but the anime original scenes were a let down, because they lacked the variety and intensity of the novels.
I think Departures did a better job of setting up the Nonaka's getting summoned back
to the Village, but the rest of the anime original content was kinda filler nonsense. They would have been better off just doing a straight adaptation of chapters 2 and 3 from volume 8.
There's some really good world building that happens in chapter 3 of volume 8 that makes most of the events in the series make much more sense, and it's a shame they didn't adapt those scenes.
The onsen trip with Chisato was adapted badly and they were real ambiguous about an important event that happens during that trip which has lasting consequences on the rest of the novels.
Basara's anime original fight against Lars was well done. This was probably the best animated fight of the series and it gives me hope that they'll be able to do justice to the fights from volume 9 onward if a S3 is green lighted.
My favorite part of the OVA came during the credits. As an LN reader, I got to see a character animated that I never thought would have ever been animated. So that was a treat for me. Overall Departures is a decent watch that sets the stage for the best arc in the series. I recommend picking up the novels though if you want the most authentic version of the story.
This did not live up to the hype that was built through months of promotional material promising an animation so lewd that genital organs would spontaneously explode out of sheer excitement and joy. I was so looking forward to Chisato/Basara having an intimacy scene that would top the raw passion of the bath scene in the first OVA. Instead we got a lukewarm, rushed onsen scene that had zero build up and failed to capture any the raw sexual emotion of the light novel. There's a scene where Basara and Mio are making out in a cave under a waterfall which is...cool? It's nothing we
haven't seen before dozens of times already. This OVA was supposed to introduce something new to the animated franchise and increase the lewdness to a level not seen in the BD and past specials. To cross that thin line between super ecchi and hentai that Shinmai had tiptoed for so long. Instead it felt like a rehash of established material that was done far better elsewhere in the series already. Just as damning is the inconsistent character designs and subpar animation that you'd expect from some cheaply strung together hentai rather than one of the most successful LN erotic adaptations of the past several years. This shouldn't happen for a well planned special that doesn't have the production constraints of seasonal TV series.
There appears to be a segment of the Shinmai Maou community that cares about the battle narrative. In that case, maybe you'll enjoy the well choreographed action sequences. I do not so I did not. This franchise is only relevant for it's fanservice, and the fanservice of this OVA was a massive letdown. I hope this isn't the last we see from Shinmai Testament and it redeems itself in later adaptation installments.