Is a spinoff of Danmachi with an alternative view focusing on Aiz, one of (for LA at least) the least interesting harem members to be given a spinoff series a good idea?.
<LA breathes in>...Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria is an interesting yet odd spinoff from the many many MANY sequels and spinoffs anime to come out of Spring 2017. LA wasn't exactly clamoring for a spinoff based on Aiz as LA is one of those fans of Danmachi wanting just more from Bell and Hestia than to Aiz though this spinoff looking at an alternative view of how events occurred in the original is a nice touch in a ways.
<LA breathes in>...Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria's characterization is focused towards Aiz as well as Lefiya Viridis voiced by Juri Kimura a fangirl of Aiz, though Lefiya is more as a similar Bell but with a similar motive of wanting to protect others by leveling up in this case trying to catch up to Aiz as well as worshiping her. Aiz on the other hand has character development in terms of her backstory and how this links to the major villain of this spinoff. This at least is interesting and gives us depth to one of the least interesting harem member of Danmachi. Aside from that, other characters are typical supporting characters with some personality to them as well as fleshing out the Loki Familia as a Guild from Bete Loga voiced by Nobuhiko Okamoto the hair-tempered berserker, Tiona Hiryute voiced by Rie Murakawa and Tione Hiryute voiced by Minami Takahashi, Riveria Ljos Alf voiced by Ayako Kawasumi and Loki voiced by Yurika Kubo the perverted leader of the Familia, which by the end of it, the majority of the supporting characters got fleshed out better than Lefiya did, especially showing us that Bete isn't the asshole jerk character or showing the Hiryute twins and especially Riveria a glass cannon badass mage and LA's favourite character in Sword Oratoria.
Now because this spinoff is having plot beats following the original, this spinoff does have some new material, that one being an interesting plotline that involves Aiz and the major villain, her plans and is probably the only interesting plotline to all the new things Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria does as it integrates both the Gods and behind the scene dealings to connecting to Aiz's past and her dilemma about being a powerful swordswomen and what her connection to this plotline has on her. The rest of the plot elements especially the slice of life are kinda a bore to constant running gag annoyance with fanservice moments any chance it gets and is just a guise for the build up and hinting to the plans of the major villain is focusing on, something even it's original somehow did quite well (albeit the original's major villain never springs into action or goes anywhere as it's a more focused look at Bell's progression to be a better adventurer, where in this spinoff, the major villain is a HUGE focus and takes a somewhat more serious take compared to the original).
Probably one of the biggest gripes Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria does is on Lefiya as a character, at first she's the fangirl wanting to be like Aiz and is a shy one at that, but by the end of the anime, she becomes a vindictive psycho lesbian wanting Aiz all to herself (slight exaggeration but the anime frames Lefiya like this and it crosses the line out of comedic effect) and sees Bell as competition. Either way, Lefiya's portrayal at first was pretty good and especially when revealed she like Bell is a pretty powerful magic user under that timid nature, but due to her static nature and never evolving or developing outside of these traits, she becomes a character LA would not root for or care one iota about. The only other character annoyance comes from Loki who does the entire yuri groping thing to Aiz or any big-breasted woman -sigh-. The only other lacking aspect Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria doesn't have compared to the original is the aforementioned slice of life moments that feels more like build up than progressing with the plot, to it's defense due to this plot simultaneously coinciding with it's original, it's kinda hard to add good flow to the plot when it needs to abide by it's original series but then LA can counter it by saying it turns into chess piece story telling with "some" substance to it and by LA sees by this later down the anime aside from a few new character development from Filvis Challia voiced by Hisako Kanemoto and Lulune Louie voiced by Hikaru Akao and a bit of world-building through Loki, it's chess piece storytelling using the original series as it's crux and the major villain egging Aiz on to be stronger or go here or there doesn't help.
In terms of animation by JC Staff, the animation overall is ok enough though there are some dips in quality at times and although the anime is rehashing moments from it's original, LA is glad they just didn't copy and pasted it just like that and given us differing perspective of certain events. The battles once again are a standout but again also takes dips in quality at times to. The character designs are polished to a certain level of detail and has the detail to be similar to it's original, typical of a spinoff in a ways, LA isn't complaining. Overall, the animation is ok enough for LA to neither rage or a praiseworthy mention about.
In terms of voice acting, the voice acting is typical fare only with the hugely expanded voice cast. Saori Oonishi as the stoic emotionless Aiz is meh in LA's opinion but she "tries". Juri Kimura, well LA is gonna compare her to Satomi Arai as Kuroko and say that she's not as bad, but she can get annoying when in obsessive fangirl mode and here's the thing, LA actually enjoyed Satomi Arai as Kuroko even at her worst of times, Juri Kimura as Lefiya has her annoying moments but LA is more or less projecting with this criticism. But once again, like the animation it's ok enough for LA to neither rage (a bit) or praise about. LA's favourite voice actors would go to Rie Murakawa and Minami Takahashi as the Hiryute twins AS well as Ayako Kawasumi as Riveria.
So Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria has a few problems with it's plot beats, some character annoyances and annoying fanserviced slice of life moments but does that mean even with it's saving graces of an interesting yet serious plotline and alternative look at similar events from the original means it's a good spinoff???...for that LA says that this spinoff is an interesting case of trying to be like it's original while at the same time whistling to a different tune, Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria is that it's not great but it's not bad either as it expands the world building of Danmachi, however if comparing to it's original, it feels a bit of a step back from it's original series, not from it's differing atmosphere and characters as even atmosphere had times where it fitted into the serious nature of the major plotline of the major villain of this spinoff and certain outside of Lefiya like Filvis, Bete and Riveria got their limelight moments but because it's trying to emulate it's original while doing something completely different instead and it does work to an extent but it's blunt execution of chess piece storytelling deterred LA from liking this spinoff as much as LA wanted to.
Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka Gaiden: Sword Oratoria, your not a bad or horrible of a spinoff but your definitely one of the more unremarkable spinoffs LA has seen.