Pretty good but really damn hard! My max score is 7 and even that took some time. The main issue is that the enemies spawn often in a convoy formation, which makes it difficult to attack, once the enemies crowd your bullet drop you're pretty much done :D But I liked it, it's graphically simple but it looks nice overall, the controls are good if a bit slow, the music is simple but ok to fill the void and the sound effects are good. Over all it feels good to play, just lacks a better defined difficulty curve ^^