Art and animation are particularly great!! The story kept me motivated throughout the gameplay. Really, the characters have personality and the world building is good.
The gameplay and systems are polished. The indicator when the character goes offscreen is an impressive touch for a game jam game!
The two things that I personally would change are the moving platforms and level restart. The moving platforms worked totally fine, but visually with a completely white background, and player movement as well, it lacked visual information--especially when static platforms were not on the screen at the same time. As for level restart, it happened so quickly that I'd lose a heart almost instantly about 75% of the time I restarted by walking off the platform, or having it break, etc.
Overall, great game! I enjoyed my playthrough a bunch :)