I never understood why waterfalls grab the hearts and minds of photographers. Go to any location that advertises a waterfall and it is guaranteed that there will be a large parking space, lots of cars, and buses with their engines idling*.
Many people, often out of shape, hike along a trail. The first action when the lookout point is reached is to pull out a camera and photograph the falls. In post-processing the images are cropped just above the pool, around which the fellow visitors had their picnic.
Waterfalls just do not photograph well. In nice, sunny weather the contrast exceeds the dynamic range of color film and of most digital sensors. Bright light also produces flair, which is a particular problem for the wet rocks and vegetation that typically surround the falls, and desaturates the color that may be present in the water. From a compositional point of view, the images are often unbalanced and there is no sense of scale, except if one refrains from cropping off the picnickers. This experience, or prejudice, made me shy away from Iguacu when I first visited Brazil in 1997. Four years ago, however, I came back to Brazil and took a detour to the waterfalls.