This is a nicely done game! I love the simplicity of the pixel style, it adds to the arcade feel. I also like the flavour of the bigger space ship that you start at, it's a nice extra touch.
A suggestion to improve would to have the player start moving down on its own, rather than wait for the first input - perhaps not immediately, because I like the imagery of the player ship being shot out from the larger one - but perhaps as the larger ship moves off screen. This second or too could also act a bit like a preparation phase/ countdown, rather than throwing the player straight into the game.