That was quite fun! The art and character design is exceedingly charming. The soundtrack is great! Although, at times it sounds more like Casio than Game Boy. The mechanics are competent and fun to pull off. I liked the mapping for each song!
(I am not very familiar with rhythm games, so my judgements might be a bit off base!)
The directions are a bit difficult to distinguish from each other at speed. Different colors might help. The same is true of 'A' and 'B'.
I think there's a reason that DDR-likes tend to have each direction on its own track: it adds another way to tell what's what at a glance. Having it all on one track can be a little confusing at times, especially when it comes to distinguishing the twirls and fast 'A' and 'B' chains in "Thrilling."
All-in-all, great work!