This is an interesting technique and quite cool that they've gotten this far with the tools available, but IMO for someone trying to produce an animated feature it's still not as good as actual animation - heck, even one of the frames where they did the comparison between the original footage and the generated image, it is clear that the general problem many image GANs have with human hands is still present. So for me this is a case of "good progress so far, but a long way to go yet".
(As someone who is a big fan of hand-drawn animation, I am ambivalent about this development - because on the one hand studios are already moving away from hand-drawn animation as few are willing to invest in it and this will contribute to that, but on the other hand it is possible that we will eventually hit a point where animation-specific iterations of these tools will be developed which can be trained on the animation team's work and thus achieve results like hand-drawn animation without the high overhead of traditional hand-drawn animation... which would also mean that animator's work is still valued in some way because the training data to establish the visual style is still required.)
I also found it extremely jarring that, as independent professionals working in media creation, they would throw out an off-hand "You can watch this anime free on Youtube" when the only "free" uploads on Youtube are blatant copyright infringements - as far as I can tell the film is still in copyright and has not been distributed for free by any of the rights holders...