It was really fun game with some awesome music! Yet it was repetitive and very soon, it will slowly get boring and later on become nothing special.
It need more variations of upgrade, and the non-stop same music start to get boring, but it was normal because there is no interval between bosses, which make this just like a mini game rather than a real shooter game.
My suggestion is; add more music and upgrade variations, add interval between the bosses like common enemy stages before reach the boss, and maybe more decent storyline.
Though the comedy and joke really got me, like how he who suppose to be a hero complain about the military who is totally not helping.
And hey! Im not sadistic, well maybe! XD