*This review assumes you have watched both of the earlier seasons.*
1. The new character designs are pretty good.
1. The animation is an utter mess.
2. The fight scenes are boring.
3. The story is badly handled and the pacing is all over the place.
4. The characters are not handled well.
5. The once stellar soundtrack failed to be put to good use and the new additions aren't amazing.
I'll get the one good thing of this season out of the way first. The new character designs are amazing. The first new spirit, Natsumi, dresses like a witch and she does so stylishly. Yoshino also gets a new armour (not exactly an Astral Dress) for combat and she looks fantastic in it. There is one more but I will end up spoiling some of the plot if I mention it, but all the new character designs for both old and new are really good overall.
Alright, now I can start picking apart this mess, starting with the animation. I don't have much of an opinion of animation most of the time, unless it is either really fluid or really awful. And DAL III falls into the latter category. The animation is pretty lackluster throughout the season and scenes quickly jump between one another with no semblance of flow, making it hard to follow what is happening. Prominently, in the climax of Natsumi's arc, a huge fight breaks out over the city but STILL FRAMES are used to depict the fight. This is absolutely unacceptable and extremely appalling.
And this leads me to my next point: the awful fight scenes. Remember in the original season, we had awesome fights like Kotori vs Kurumi? Yeah none of that here. With how big Shido's harem has grown and no effort to try to make any of the captured Spirits busy, they all end up gathering at every fight. And as the saying goes: too many cooks spoil the broth. Every single fight scene in DAL III is just each Spirit taking turns to use their abilities once and then sod off. There is even a specific order for each Spirit to come in and specific roles each Spirit takes up with no variation to freshen things up. The Yamai sisters always attack first and will be at the frontline. Miku always provides long-range support from the back and Yoshino just creates walls of ice for defence. Tohka always goes last. This cookie cutter formula makes the already mediocre battles even more boring. Having every Spirit be present in every fight prevents them from reaching their full potential and standing out, thereby ruining the well-established powers and abilities from previous seasons. And this is a shame as season 2 made an effort to reducing the number of Spirits around for every fight. For the Yamai sisters' arc, it occurred in a school trip so Tohka was the only allied Spirit available. For Miku's arc, the Spirits are brainwashed by Miku so that Kurumi, Mana and Origami have a chance to show off her abilities.
The story is also another trainwreck. The pacing feels all over the place. Natsumi's arc felt a little too long, and the last episode was supposed to be an ENTIRE VOLUME'S CONTENT?! The last epsiode just came out of nowhere and did nothing but cheap fanservice right after the much more serious second arc of the season ended. Why not just go for ten episodes like last time? Shorten Natsumi's arc and drop that last episode and the pacing will be a little better. The story elements are disappointing as well. The second arc of the season has heavy use of time travel but the consequences of time travel is not handled well. The only parts of the story that I enjoyed are Natsumi's game and the new world caused by changing the past. The rest of the story continued to be DAL's formulaic story structure which has gotten old.
The characters are also not handled well. Most of the captured Spirits do not develop at all throughout the season. Natsumi is also a very unlikeable brat who also does not undergo any character development, remaining as the self-loathing, tsundere loli she started out as. The Origami in the new world in the second arc is a breath of fresh air, but it is so disappointing to see Origami going back to normal by the end of the arc.
Lastly, the soundtrack. DAL III continues to use the soundtrack poorly after season 2. For example, battles do not last as long as the music used, causing the music to be abruptly cut so the end of the piece can be played. Sentimental pieces like Secret is hardly used, if at all, and those pieces are half of what makes the soundtrack of the original season so good. The new OP and ED are reminiscent of past OPs and EDs but neither is particularly good. Natsumi's theme is the only exception, with the playful tune fitting her mischiefs.
As this is a sequel, I am rating it against the standards set by the previous seasons. And this season just keeps shooting itself in the foot. It fails at nearly almost aspect. Even though I love the original season and somewhat enjoyed the second, this season is quite the slog to get through. DAL III marks a new low point for the anime series. At this point, it may be better to drop the anime and follow the original LN instead.