I would've loved to see some part of the background that remained stationary relative to world (instead of relative to the camera) so that I could have a frame of reference for how fast I'm moving. As is, there is no visible difference between moving up and moving down. When an asteroid is in frame, you can use to see your current acceleration, but velocity is completely invisible, with the only way to tell being when you hit your max speed and stop accelerating.
The controls need you to have your hand in three places, though. You left hand is on WASD, but your right hand needs to use both the arrow keys and the mouse. If you need someone to frequently use both WASD and arrow keys, it's usually best to have everything be controllable without the mouse so that the player doesn't need to constantly move their hand back and forth. Alternatively, do everything with the mouse instead of needing the arrow keys.