It's a fun game. There are some issues, but they didn't affect my ability to complete the game.
So, the first is that the player movement has inertia, which makes it more difficult to be precise. This might just be personal preference, but I prefer space shooters without it.
Collisions can lag the game. This isn't a big deal, as they don't happen frequently. Oh, and the game didn't exit properly for me.
There don't seem to be many invincibility frames. They're not necessary, but I like having them.
Controller is recommended for a reason. The keyboard controls are not very good - I beat the game using them, but they feel very awkward to use.
Other than that, it's a fun experience, albeit a short one. It would have been nice to see more levels, but it feels a little greedy to suggest something like that for what is probably someone's first released game.
Good work, commander! I look forward to seeing your next game.