I really like the new prologue, it really shows us that Kobu genuinely cares about being a good Demon King and tries really hard but still struggles with it which leads to inevitable burn out, instead of the old version he just seems like a spoiled brat that didn't care about anything other than himself.
Most of the changes were perfect, although I have to ask why did you cut out the beginning when Kobu was little, did it not fit with the story or was it just moved to later in the story.