Most backyards and landscapes don't have the room for a pond and waterfall this big. And even if they do, most folks wouldn't consider a water garden this size. Aside from needing professional design ideas and construction, material costs could be quite expensive.
While it may seem that a water garden this size would require a lot of maintenance, if it is designed properly as an eco-system, it generally takes care of itself. Just as in nature, with a natural balance of fish, algae, aquatic plants, flowing water, and other living organisms, a pond or stream, can remain healthy and clean with very little maintenance. So actually, if it's built right in the first place, a big pond and waterfall like this will only require a little maintenance and upkeep.