Graphics: Very nice backgrounds and character models, they really did stand out. The particle effects were nice too, I really liked the smoke.
Animation: Very smooth and a pace true to Space Invaders. The projectiles glided along the screen as one would expect, no physics errors with them, and the particle effects were nice.
Sound: Nice little bleeps and blips, but there was room for improvment.. this includes background music. But overall, it all fit together.
Programming: Excellent programming, no bugs found and the physics were perfect.
Extras/Plus: I liked the fact that you replaced the classic laser projectile that the ship shoots with a missle. Very nice.
Overall: Yes there are better versions of this game out there, but this one surley doesn't fail. A worthy addition to the Space Invaders emulator collection indeed.