Review of Zoku Owarimonogatari
Zoku Owarimonogatari is a mindbending filler-yet-not-filler, psychological-yet-not-psychological mystery that serves as an endcap, and an excellent one, to the 94 episodes and 3 movies that came before it. And, before you even think about watching this one, yes, you DO have to watch all of those to follow what's going on here; aside from the three prequel movies (which you should watch anyway; they're great), every single bit of the Monogatari series preceding this builds towards this one conclusion, this one story that really doesn't change a single thing, and yet is still an essential watch. The story is simple-- Koyomi Araragi falls into a mirrorworld that looks and sounds like his own, with all the same familiar (entirely female) faces, but with each of them being altered in bizarre ways. It's an ontological, yet pointless adventure that'll have you scrounging around trying to find the secrets behind this mysterious world, but laughing the whole way through. It's silly, the tension is minimal, and we get one more appearance by a whole host of great characters. I'd say, despite the massive cast, almost everyone gets their chance to shine with one last bit of character development, though Kanbaru is reduced to a (nearly) non-speaking role since, chronologically, she doesn't get her character resolution until after this takes place, despite this being the finale... this series is weird, okay...
In terms of the metafictional self-aware questioning of its story's own existence, Zoku Owarimonogatari is essentially this series's equivalent to Madoka Magica: The Rebellion, which was not-coincidentally also made by Studio SHAFT. As superfluous as a Fun Mirror World Finale is, it encapsulates everything we've come to love and appreciate about the Monogatari series so far, and it's great!
Also, this is one of the longest animated movies I've ever watched, just under two and a half hours. It was long enough that when they made a series out of it, they were able to split it into SIX episodes. Do we ever really need to live in a world where animated movies are this long? Please, I loved this, but do not make this a model for success.
Also also, this appears to have been directed, like actually directed-directed, by Akiyuki Shinbo, something that hasn't happened for a SHAFT production in ages; he's the chief director for the whole studio so he gets co-director credit for most every SHAFT work, but he is usually not directly involved in the productions beyond that chief role. But I scoured the credits and couldn't find anyone at the top but him... How strange!