The thick, dense undergrowth actually makes it difficult to see the giant pandas, and so most zoo visitors have to patiently stroll around all 4 exhibits in order to catch a glimpse of the world's most popular zoo animal.
Giant Pandas aren't one of those animals that if someone can't see it they'll go on to the next exhibit. I think people would wait for hours just to get a glimpse of a giant panda, even your average visitor.
@PAT: when are you going to be able to visit the giant pandas at the Adelaide Zoo? Their enclosures are not comparable to the brilliant exhibits for pandas at the National Zoo in Washington, D.C., but pandas still bring in massive crowds and are fantastic to see for the average zoo fan.