I think the game is fairly well balanced and the visuals feel very arcade-y!
I found troublesome that when leveling up, the UI pops up allowing you to interact with it instantly. This can cause the player to accidently click an upgrade that was undesired. (which happened to me more than once :P) Adding a second, "confirm" button is always a good way to make sure that doesn't happen.
Otherwise I've got nothing to say, solid jam entry!