I just played through the demo, thought it was pretty good overall. I think the sprites (which are very cute) along with the winter aesthetic are probably the demo's strongest point overall. Beyond that I also thought Trucy in particular was written well. I'm only about midway through AA5 myself, but her characterization here seems closer to the more complex character hinted at for her in AA4, than what I've seen of her in 5. Beyond just her characterization I also liked the concept of seeing a character knowing of and trying to work against the Magnatama. I also enjoyed the full dialog for all presents.
As for some constructive criticism, as another commenter said, I think the contrast on the backgrounds is bit blown out, particularly the hallway and stage. I found it a bit odd that we didn't actually see the interaction where Maya gives the Magnatama to Fran, which feels like it'd be kind of an important moment, though I suspect that may be planned to be included in the full release. Only other thing I could think of is maybe a little more set up/establishment for Maya and Franz relationship since we otherwise have no context for it. Though tbf the implicit set up is fairly clear, so it might not be necessary idk.