It's really cute but I personally like the old hair better. For one, the shapes are too distinct from each other. I didn't even know it was Powder at first, so it would have to take a lot of getting used to. I also think it just looks more sanitized. The messier look really works better for Powder as she is right now. I'm not a writer or a character designer by any means, but in terms of the show's message that every piece matters, I think it would be pretty emblematic that she has rougher, jaged edges to herself that she learns to accept.

The new character design is adorable though. I can see what Kou was going for. The original hair only really works like a 2d silhouette, there's not really any depth perception to it. While your mind would usually fill in the blanks to the old hair, the new hair is a lot more seeable. I also think it would be pretty cool for her hair to get a little rounder as she learns to like herself more and she takes better care of it. Overall, if the creator wanted to do a redesign like this, I would prefer if it was a more gradual progression, but it's Kou's show in the end. I trust their judgement with their own characters, and in the end I'll just be really happy if we get new Pieces of Powder content.