The Nest of Evil makes me wanna scream.
I think that the two different playable characters is cool but I'm not sure if they were able to do everything they wanted to do with it. There's only so much you can do as Charlotte that you'll often be playing as Jonathan since not a lot of monsters are weak to the magic that she can use.
The quests were cool even though I didn't get all of them done before beating the game.
I think that the castle is a lot smaller in comparison to Dawn and even Aria, and the paintings don't really make it feel that much bigger.
Jonathan and Charlotte are fun characters and it's nice to have protagonists that are (comparatively) more relaxed after playing three games in a row of pretty serious main characters.

Beat this after three years of chipping away at it and I can say it's really good but also flawed. There's a lot of typos and weird grammatical things especially towards the end (the screen you get when beating all puzzles says "pazzle"). I really hate that you can't turn off autocorrect even if you turn off all assists.
The songs are good, though I only ended up listening to two of them most of the time. I haven't gotten the chance (or motivation) to hear them outside of the context of the game, though.
I liked it and I would like to get into more themed Picross/nonogram titles if they had stuff I liked.