I had a lot of fun playing this. The only criticism I have is with the progression of difficulty: It starts out relatively hard (especially the first boss fight), but becomes increasingly easy when you get the resources to buy high-end weapons. The whole final star system was extremely easy to beat because of this. Also, it would have been nice to have the option of getting back to the main menu during a mission. As it is, you have to alt+f4 if you want to abort. (Last point: Full screen didn't work for me, but that may be a hardware problem on my side. My graphics card don't seem to be fully supported by Debian.)
A great little space shooter.