Really good game!
You deserve a 9!
I could make a big-ass review here, but im tired now, so ill just say the important things:
GOOD THINGS.
+Fun gameplay
+Not repetitive levels
+Nice music
+Cool effects on different surfaces / areas
BAD THINGS.
-Personally, i think the "door-ish" sound that plays when you hold the mouse button to aim is pretty annoying.
Nothing else to say, good game.