Well I would give it a 6,
You could rip people in half, tear their heads off, all sorts of 'Exicution' moves on people.
But your combistick took like 5 hits to kill someone. Sometimes if you stabbed it straight through them they would still be alive.
And it got kinda too futuristic, everyone having plasma guns, even humans, very thick armor, and fighting a human/pred person at the end. Kinda made it pretty stupid, and bossess having TONS of health, no human or anything could stand that much beating.
Although you could stalk, cloak, use vocal mimicry, and lure some people to you, like on my favorite level, "Dead Men Walking".
The game was Predator and had some Predator like featurs, but had abunch of flaws, so yea I give it a 6.
And the added weapon called "The Maul" which I didnt really like, I think it was trying to give predator a more "Bad A" look, same with the Glaive.