I love a good bullet hell.
A few things I think would make the gameplay feel better are to reduce the player speed slightly, normalise diagonal movement so that you're not traveling at 1.414x max speed, and increase the hitbox on the lightning bolts. With the current player speed I found myself constantly doing circles around the lightning bolts trying to collect them because it wouldn't quite line up. Would also love gamepad support!
I loved the scripted boss AI in later levels too, they felt a lot smarter than just "shoot at player".
Music is a bit repetitive and doesn't fit the gameplay IMO.
Good game!