I really like the feeling of the controls and flying around the level. The music was awesome too and really fits the visuals and gameplay well.
It felt like the gameplay was lacking some complexity. Maybe add some additional defense options like a deflector shield that you have to point with the mouse or maybe the ability to drop chaff for the missiles to run in to. You could give these mechanics a limited availability and require the player to pick up resupply items.
The other thing is the camera makes it hard to see what's coming up in front of the player, especially when you start to move faster. Maybe have the camera stay more on the center of the player or possibly zoom out as you get faster.