What happened with the new character design for Sebastian? He looked too soft for a demon. A lot of people also complained about how his eyes looked odd. I feel the gap between his eyes were too big and his face that looked rounder. If you compared his design from Season 1 up to the Movie, you'll get what I am trying to say. He looked more devilish, hot, and intimidating. Moreover, the bright color tones were a contrast to the gothic and horror atmosphere we got in the previous seasons. It made Black Butler: Public School Arc look like a normal slice of life anime rather than mystery and supernatural.
In all honesty, I am still glad that CloverWorks wanted to adapt this series that had so much potential. In terms of animation, they nailed the movements. It was smooth and neat. I just wish they could change the character design and stay true to the previous ones for consistency.
In terms of story, it was okay. Nothing bad, nothing excellent. I hope that they will do changes to the next arc.