It is a good story and some good action scenes, but the film seems pieced together and skips more than a few details. (This could be due to editing.) It feels like the viewer is being dragged through the story as quickly as possible.
While it is very promising and could be a great anime, it could use some more back story and fleshing out. It looks like they could possibly do a second film, but I think it would be better suited as an episodic anime where they have time to build the characters, their relationships, and the story arcs.
I still recommend watching it!