MoGiFeedback

Could use grazing SFX and particles. There might be some already, but against the lasers it's noticeably silent. Graze cheesing lasers is fun and makes you think you're good, even if you're not.

I could not find the bomb/life counters at first glance. Or rather, I couldn't tell what they were on first sight. Maybe during tutorial, point this out?
Also, bombs don't replenish after death? It's frustrating to burn through lives on a particularly hard pattern.

Point pickups are very similar in color to bullets.

You can cheese the midboss's last pattern by playing in her face. This may be intentional.

If you die right before the cutscene, you can't collect the two bursts. I think the auto-pathing to the center of the screen just so happened to go over one.

Burst and Fragments have the same shape. This could be confusing. Also, since the level is so short, the player never actually collects a life up or extra bombs. Fine for the game, but on demos (esp a short one) consider handing out extras of everything.

Bombing doesn't give invulnerability (you can run into the lasers).

I've only every played touhou for shmups, and used KB exclusively. So KB controls felt fine.

My score on my first clear was 1914456, but I've never played a shmup for scoring, so I can't offer any feedback about it. Sorry.

As for overall difficulty: if you don't understand how to read patterns, the boss could be a bit hard for a first level (if that was meant as level 1). Once you filter out the excess, it seems more reasonable, but then again isn't that the essence of shmups?

My comparison here is EoSD (https://www.youtube.com/watch?v=9RKUIrjRAcs). Rumia there has a final pattern that's at most 21 seconds long. Again, I was at best a casual, so feel free to consider or ignore as much of my opinion as you'd like.