As a shooter, it works. I've been playing Touhou recently, so that helped me. As others have said, there is virtually no lag, so any time you get hit, it's probably going to be your fault.
That said, I have some criticisms:
1. Upgrades felt bland, and it would be nice if you could pick from different weapons rather than being stuck with 'shot' 'spread' and 'missile'. I'd also like to see some color in my own shots, not just gray everything.
2. Upgrades to the ship seemed insufficient to deal with enemies, especially when one goes the secret route. It's rather difficult, and while it is understandable that the secret path be harder, I have not as of this point beaten the boss in the secret path. More health, please!
3. The story really doesn't make much sense, as far as I have seen. Obviously, it would be no fun if there were no shooting in a shooter, but why send attack drones out? Of course people will take that as hostile and respond in kind. Even the boss ship shoots you in the secret path. Maybe the people on-board thought the drones were being destroyed? That's the only explanation I can come up with at this time.
Now, I don't want this to seem excessively negative: you made the game in 48 hours, which is extremely impressive given the high quality overall, but would it be impossible to update it?
If an update isn't necessary, and I'm just not a good player, someone tell me, please.