Episode 12:
Finished anime Deca-Dence today. It was quite a ride.
Generally, I do not like when shows break their own rules. Usually it does not rally work, looks sloppy and used simply because creators do not see where to move the story and simply do not wish to finish it just yet. Or they never really had a strict set of rules, which implies little thought into the setting or lore.
Deca-Dence is a rare exception: it starts breaking rules from the first episode even, but here it makes sense, because of "meta" theme(s): what we see is just "lowest" layer of existence described in the show, and there is a higher one, which works differently and we do not know anything about it and how it was created. Some revelations in the story could remind you of Shingeki no Kyojin.
And it's not only that, that can remind you of Titans: it's also the fighting that takes place in mid-air. It's more futuristic and bends physics quite a bit more, but it still looks quite good an dynamic. And while the story itself is not so much about fighting per say (although about perseverance in general), fighting scenes fit the flow (which sometimes failed in Titans).
The show is definitely unique in its presentation, though. Yes, it can also remind you of Tengen Toppa Gurren Lagann in some scenes, but as with Titans it looks more like the show took inspiration from it.
Some may find it a bit simple and predictable after a certain set of "rules" are broken, but I do not think you will have enough time to bother with it. At least, I did not have time to nitpick while watching it.
So watch it. Just know, that Natsume looks better with short hair.