While I like a lot of features in this game, I do have minor complaints.
-When enemies spawn, they spawn rather quickly and it can be a bit of an annoyance to have one spawn in your path or on you, dealing damage immediately.
-Hitbox feels a bit large for these type of games.
-Lack of keyboard controls (eh, just a preference, not really a big issue)
Aside that, I praise you for your upgrade system, shop system, the pace of the game seeming fast and enjoyable, the boss fights feel just about right. Would be nice to see more of your work later on and perhaps add on more shot types or something along the lines.