I thought it was cool to see them try that (it was certainly better than putting the guy on top of a pickup truck, which they did later), but personally I thought that scene in GAH proved how the "real thing" doesn't look nearly as good as we imagine it. The way everything ripples violently in the wind like that, and the way the person's face gets all stretched and contorted, just doesn't really go with the graceful image I have of Superman.
Well, of course the closeups of the actors' faces would be shot in the studio, since obviously it would be stunt performers doing the skydiving, not the actors themselves. That's the way it's routinely done in James Bond films and the like, so I assumed that went without saying. But having it be actual skydivers in the more distant shots would really help give a sense of realism and dynamism to the scenes that greenscreen work just couldn't achieve.