good stuff:
the theme, the general idea, the level design, the overall graphics and soundeffects, the enemy movement/design, the game-mechanics (like the shattering glass and movable objekts).
bad stuff:
sometimes the aiming upwards and downwards is a bit difficult, the soundtrack is good in the beginning, but gets a bit weird, when it repeats the 8th time
but all in all, the best game i played yet