Design-wise, the bullets feel pretty random. Consider making patterns that are deliberately just wide enough for the player's hitbox to fit through. Generally I felt like I had to zoom my vision out and avoid bullet walls as a whole, rather than trying to weave between them (unless that was intended). That also means the full-speed movement was more useful than the "focus" (shift) movement.
Minor points: the music stopped looping after a while. Also, there should be a longer pause after the game ends, because I accidentally pressed a button to restart and couldn't see my score.