Wild to think that it's over after so long. This series wasn't always good (particularly season 3 and 4), but this was an alright final season.
I feel like some interesting concepts haven't been fully explored and loose ends not being fully tied up. For example, the invertion of the Spirits kinda ended up being a nothingburger, same with Tohka being a Pure Spirit.
Kurumi's goal was kinda left out at the end and we weren't really shown a proper conclusion for it imo. Sure, Mio died, but not as an act of revenge. I would've liked to see Kurumi coming to terms with it all. Seeing Kurumi at the end though, enjoying the presence of cats was cute.
Same with Artemisia. Supposedly brainwashed, but that was all. No further info on what happened afterwards with her.
I also would've liked to see what happened to the world now that, assumedly, Spirits are no longer a problem.
The whole Isaac Westcott thing was a little bit meh as well. He was more of a nuisance getting in the way of the actually interesting stuff than a good additional villain.
While this season was okay at best, there were a lot of interesting and good ideas here, even if, imo, they didn't come to fruition properly. Unlike season 3 and 4, this season remained competent when Kurumi wasn't directly involved. The OST also still is one of the best things about this anime. Some really solid themes with great arrangements with an awesome throwback to the 1st season's OP at the end. The OP and ED were amazing too, despite being a little spoilery at first. There were some great heartfelt moments this season as well.
I don't think I can give this season more than a 6.5/10, but the anime as a whole would probably be a 7.5/10 (which may or may not be skewed by nostalgia for season 1 and 2).