hmm
It's obvious alot of effort went into this, some good attempts at fbf animation. Although your art is generally ok, it lacks detail, you need to add better shading and better faces for a start.
For fbf, i'm not saying there isn't any, but you could of done alot more. You only used it for small parts such as faces and gun movements, when there should of been running animations and turns to add to the action. And one person here mentioned screen flashes were overused, i think he was right as it was obviously another shortcut when, for example, you could of shown the fist hitting the face.
You know the sound was bad, and you need to use darker reds for blood and should check some movies for how it falls. If you practiced a bit more, you could be really successful.
As i said, some good effort here, but not excecuted well enough. And stop arguing with reviewers (the good ones anyway), they're just voicing there opinion.