It was good. Studio Durian and the director Kiyotaka Oshiyama did the manga justice and managed to add some additional material that makes the 75 min runtime feel good enough. Some scenes felt rotoscoped, if so I think it was used well and conveyed the emotion. The voice acting was great. The animation of the 4 panel manga surprised me, but it was a welcome addition. The soundtrack is a gorgeous piano throughout. The emotional moments hit like a truck.
My only mild criticism of the movie is that the ending feels a little too drawn out, compared to the manga where the punchiness of the panel transitions really sell the emotional gutpunch there.
But otherwise it’s a brilliant movie that I’d highly recommend, especially if you’re curious about Fujimoto’s (the original mangaka) work but aren’t feeling the schlocky-ness of Chainsawman.