Really fun! For something made in 3 days this is quite impressive. Also, I'm not sure if this is intentional or not, but being able to use your spin move as a double jump is actually really fun mobility-wise,and helps make Youmu just feel quite nice to control (but also it lets you exit the main stage when combined with the dash, which I don't think is intended?)
Also, I have no idea what this would actually entail (or if it's a remotely reasonable thing to do), but honestly this makes me wonder if it's possible to mod Youmu into RoR.