I had a lot of fun with this one, even if Remilia took several tries. My reaction speed left a bit to be desired during her fastest attacks. The checkpoints per boss were greatly appreciated. Moving the characters around does a lot to make it feel like an intense fight, and makes good use of the 3D backgrounds. And it is just very satisfying to click furiously after a sequence of intense blocking. Good gameplay loop.
As other people have noted, the lack of music is unfortunate. This does feel like a rhythm game. In fact, correctly blocking a chain of attacks started to sound a bit like a tune. A beat-em-up where the music is played by blocking and attacking at the right time would be pretty cool.