quite good
graphics - some of the asteroids were kind of low contrast and difficult to see, but most were good. turrets and crosshairs looked good.
style - pretty cool, although it allowed for asteroids to go off to the side of the screen and disappear, but i see how that's about all you can do with them.
sound - i give it a 10 because you allowed me the option to turn it off, not because i don't like the music and sounds you picked, but because i prefer to listen to my own music while playing games, so thanks.
violence - BANG BANG BANG BOOM!!! it's a shooter, if there wasn't violence i'd be pissed.
interactivity - the menus worked well and the game ran smoothly, i understood how everything worked right away. good job.
overall it was cool, especially the physics of the asteroids, but after level 17 i had all turrets with blue lasers as primary and antimatter missiles as secondary. this made me pretty much unstoppable. i think that to add more variety the primary and secondary weapons sets could be entirely different, primary focusing more on speed and accuracy, secondary more on explosions and area of damage. i liked how the mini-turrets functioned autonomously, but i would've liked to have been able to upgrade them as well.
this was one of the better defence games i've played.