I'm kind of surprised by the view count which seems unusually high for this sort of movie. Is that the nudity on the poster ;)?
Personally I never thought this would see a release anytime soon with anything English but here we are!
Anyone that is not weirded out by the plot synopsis or thinks that makes a good movie will probably enjoy this (I'd add necrophilia and rape to the not-be-offended list though).
The weakest part of the movie is definitely the wrap-around story which serves as an excuse to tell us the story of the "Gun Woman" in the form of flashbacks. The mute woman itself is portrayed quite well by "Asami" which seems to have made the switch from the JAV industry to the gorefests of Noboru Iguchi and friends. You can definitely see her transformation from crackwhore to assassin...
The action is solid and there is plenty of blood. The budget is notably limited and the CG barley passes. Still, it's an entertaining movie that is as sleazy as it sounds (the IMDB rating is falling through the roof though).

PS: I would also like to know how Tatsuya Nakadai got cast in this, it's kinda funny.