This cinematic conclusion to the anime series is brilliantly animated, with high production values. However it makes some terrible choices that turn it into a randomly-connected movie rather than a conclusion to the series.
Weak spoilers follow.
Firstly, the movie is oriented around a conflict between a secret organisation (actually two) and a rebel movement – these are created out of whole cloth and basically call back to nothing in the original series, it’s essentially a cliche imported for its formula. The Furukimono and their agreement – one of the key mysteries of the TV series -disappears into the background.
Secondly, Saya is unsociable for the entire movie. Given that Blood-C was about the transformation of a friendly, ditzy girl to a vengeful killer as her environment is torn up around her, the movie abandons that theme altogether.
There are some plot twists, but the entire movie wasn’t coherent enough; the final enemy spends more time appearing than being defeated; the ending is too short, and doesn’t resolve or explain anything.
So, a very pretty miss. Watchable if taken on its own, but nothing groundbreaking then.