Would the movie had been better had James Cameron's actual screenplay was used?
James Cameron initially wrote a script and it was basically a full-blown James Cameron version of Rambo II. It had more characters, more tech, and was all in all, a bigger movie.
Sylvester Stallone didn't like that and rewrote the script to make a simpler, cheaper movie. Then they had George P. Cosmatos involved, a director with an already poor track record, but he was probably also studio controllable.