Yeah, I just discovered this game last night, barely made it past Phase 3 the next night, then just gave up and watched a vid and couldn't comprehend the very end of the fight.
And this is coming from someone who regularly plays various bullet hells, and can understand this shit
Edit: Corrected assessment of how much of Phase 4 I could understand (Originally said I couldn't understand most of the second half, but that might've just been fatigue from runs I did where I struggled with the lack of I-frames)