I really enjoy the movie despite the problems, but it does have huge problems. And thankfully some of the stuff (no swearing in the 23rd century) has been retconned.
Edit: Since I already opened this can of worms, my biggest problem with ST IV, by far, is that Kirk and his crew have major difficulties adapting to 1980s Earth when not only do they not have that difficulty when on clandestine missions on entirely alien planets, Kirk and Spock do not seem to have a problem adapting to 1930s Earth in City on the Edge of Forever.
It kind of makes them seem inept and it bothers me.