I liked it! But there are some issues I feel could be addressed.
First, I think the levels are a bit too long. And there's not a lot of variations with enemy types or formations (most of the time they seem random?), so the levels end up feeling a bit boring. Also, I think being hit once and you die is not the most appropriate for a game jam. I wanted to keep playing, but losing a life and having to do it all again is pretty demotivational... Especially with the long levels!
But the system for powerups (where you get more powers that eventually run out) seems very interesting! I would like to see it expanded a bit more :). The boss was also pretty interesting! But I feel that the phase shift is a bit too sudden. Usually in shmups their phase changes are a bit more signalled, I think.
Also, I felt that sometimes the game didn't respond to my commands? But it's not like it happened a lot. I played on Windows if it matters.