It isn't always a good idea. It is unable to resolve situations where there are two second parties with competing interests.
Here's an example that is perhaps one of the "classic" ethical quandaries. A woman is pregnant. A doctor examines her and discovers that for, whatever reason, if the foetus is not aborted the mother will certainly die. Who is the "other" of the golden rule here? The mother or the foetus? Unless the mother is genuinely willing to sacrifice her life to give the child a chance of survival, the golden rule paralyses the doctor by stating that the child must be aborted, otherwise the mother will die, and the child must not be aborted because that would be destroying the child's life.
Alternatively, it is not a "good idea" when one is dealing with a definitely morally culpable person. Say you are (for whatever reason) in a position to obstruct the plans of a person who is bent on committing a series of murders. If you were to obstruct his actions, you would be causing him displeasure. Of course, if you didn't obstruct him, you'd be causing displeasure to his victims. There are two answers to this:
Firstly, one could be overly legalistic and say that obstruction is an act and failure to obstruct is a mere omission, but that's just stupid and wanky.
Alternatively, though, if we say that we're going to require you to stop the murderer because, although you're causing him displeasure, you're preventing far greater displeasure on the part of the victims and so we ignore the displeasure of the murderer. Which in this case most people would agree with as being the moral course of action; however, we've now replaced the golden rule with utilitarianism which has its own difficulties. Aside from the fact that it requires one to assess the quantity of potential happiness to be caused by any course of action, it creates a kind of sanctification of "happiness" or "pleasure" as being the most important consideration in any situation.
This obviously applies equally to the golden rule. The fact that we've all seemed to agree that taxes are a "good thing" and that we ought to pay them, despite the displeasure they bring us, suggests that we agree that happiness isn't the ultimate consideration. Perhaps part of the problem is that "happiness" does not describe a single kind of emotion - it ranges from satisfaction to ecstasy, which I submit differ not only in degree but in character. You can't compare them in any sense that "if I make six people content then that is worth one ecstatic person", much in the same way you can't say "sonata form is worth the same as the theory of relativity".
Anyway I'm not proposing to solve the problem of ethics in an internet forum thread; it's just a good thing to consider. There is no perfect ethical framework; the golden rule is just as practicable on an everyday basis as utilitarianism or deontology or any other kind of popular ethical system.
