Easily the best use of the theme I've seen in the 100+ games I've tried so far. I loved the PaRappa styled animation for the boss. I loved the tone from the text and the music and the lighting and color palette.
My only critique is that the fights felt like they could go a bit long with any mistakes. I had a few rounds that felt like a war of attrition that was based on the enemy making a lucky mistake rather than rewarding me for effective play/not making mistakes.