I did feel that the sun and the boss' attack graphics' squaryness clash with the overall smooth lines of the games.
If you want to introduce it as a theme, I would suggest you take damage from anything that looks squary, so that means the sun wouldn't look that way.
It looks nice, but it clashes, and as such I spent most of that level looking at the sun and expecting something to happen with it.
Wonderful graphics and animation, though it could really use some in-betweens.
About gameplay, although it's standard platforming it really works and I liked the theme and flow. Hover and jump key could have been the same though, but even if it's not it still works.