Pacing
The mix of graphic styles is a good start, but the forms do not look solid. To refrain from spoilers, I'll just say that the penciled area could have been integrated a little better. The most obvious problem with this piece is the pacing. Scenes went on too long to highlight the music. Ultimately it made it look like you didn't have anything else to add to the story or draw. And, an over-use of slow-motion for those particular scenes. Either develop those scenes more or make them shorter. Also, the subtitles were hard to read, though not impossible.
There's a good amount of potential here if you just focus more on the story than the special effects and music.